What is Machine Learning vs Deep Learning?

What Is Machine Learning?

Machine learning works by letting a computer learn patterns from data and then using those patterns to make predictions or decisions. It improves with experience without explicit programming. Data is the fuel for ML. It starts with a problem, or a question you want the system to answer and uses the collected and normalized data in a model (an algorithm that maps inputs to outputs). Each model has parameters learned from data and hyperparameters chosen by humans.

Common ML models include:

• Linear regression: ML algorithms that model the relationship between a dependent variable (what you want to predict) and one or more independent variables (inputs) by fitting a straight line (or hyperplane) to the data. This model learns by making predictions without initial coefficients, measuring the error between predictions and actual values and adjusting coefficients to minimize errors.
• Decision tree: A class of ML algorithms that make predictions by learning a set of if-then rules from data and then splits data into branches based on feature values forming a tree-like structure. Each question is a decision node, and each answer leads down a branch until a leaf node gives the final prediction.
• Random forest: A model that combines a collection of decision trees to make more accurate and stable predictions. Each tree trains on a different sample of data and the final prediction is an average or a majority vote on the best output.
• Support vector machines (SVMs): A class of ML models used for classification and regression that find the best boundary that separates data points into different classes.

Machine learning models learn patterns more effectively with feature engineering, a process of transforming raw data into useful signals for a model. A feature is an input variable (numerical, categorical, date/time, text) used by a model. Good features can improve accuracy, interpretability and reduce training time.

The Four Types of Machine Learning

• Supervised learning: A machine learning approach where a model is trained using labeled data (data that includes both the input features and the correct output). The model is shown examples and is told the correct answer to learn a mapping. Common supervised learning tasks include classification (spam vs not spam, or disease presence) or regression (price prediction, sales forecasts).
• Unsupervised learning: Machine learning where a model finds and learns patterns from unlabeled data that has no predefined answer. It can find patterns by grouping similar data points together, reducing the number of features, finding anomalous or rare data points or finding relationships between variables. Real world examples include customer segmentation and anomaly detection.
• Semi-supervised learning: A machine learning approach that uses a small amount of labeled data together with a large amount of unlabeled data to train a model. The labeled data anchors the learning, while unlabeled data helps refine the decision boundary. This approach is commonly used for image classification, medical diagnosis and speech recognition.
• Reinforcement learning: Trial and error machine learning where an agent learns by interacting with an environment, taking actions and receiving rewards or penalties — rather than learning from labeled examples (e.g., game-playing, robotics).

What Is Deep Learning?

Deep learning is an ML approach using multi-layered artificial neural networks to automatically learn complex patterns from large amounts of data. They are called neural networks because they mimic the human brain's neuron structure. It is one of the most powerful approaches to building AI systems.

With deep learning, humans don’t design the features to learn from, the models learn representations directly from raw data using many layers of neural networks. The layers build a hierarchy of features and include an input layer, multiple hidden layers and an output layer. Each layer applies weights, adds a bias and passes through a nonlinear activation.

Common Types of Neural Networks

• Feedforward networks: These are the simplest neural networks and represent the foundational architecture for neural networks. Data flows in one direction from input to hidden to output layers, so they are best structured data, regression and classification.
• Convolutional Neural Networks (CNNs): Networks specialized for grid-like data. It uses convolution filters to detect patterns like edges and shapes. It’s best for image recognition and computer vision tasks.
• Recurrent Neural Networks (RNNs): Networks with feedback loops that maintain a hidden state, designed for sequential data like text generation, speech recognition and time series forecasting.
• Generative Adversarial Networks (GANs): Used for generating new realistic data by training two neural networks that compete with each other. One network creates fake data and the other tries to detect it, so both improve through competition. Examples include image, audio and video generation.

How Machine Learning and Deep Learning Are Similar

Both ML and DL fall under the AI umbrella and are closely related because deep learning is a subset of machine learning. They share many foundational principles, workflows and goals. Both learn patterns from data and aim to make predictions or decisions based on that data.

When they learn from data, both can improve their performance as they see more data in an iterative learning process. And both can generalize from that data to new, previously unseen data. Both ML and DL require training on historical data, validation to tune parameters and testing on unseen data.

And both can be applied to classification, regression and clustering problems.

Data Requirements and Feature Engineering

While machine learning and deep learning have many similarities, they have different data requirements and feature engineering efforts. ML often works well with small to medium structured datasets, but performance depends on feature quality which requires human-led feature engineering to identify relevant variables.

DL depends on large amounts of unstructured data (images, text, audio) and the scale of examples directly impacts performance since DL performs automatic feature extraction with minimal human intervention.

Domain knowledge and feature quality is essential with ML, while models learn features internally with DL, so data scale and infrastructure become more important.

Computational Power and Training Time

It’s useful to compare the compute requirements and training time needed for both ML and DL as these are the factors that most affect cost, iteration speed and product feasibility of your systems. Traditional ML models can run on standard CPUs with lower memory, while DL requires GPUs or TPUs with high memory for efficient training, so infrastructure costs will be higher with DL.

ML models train quickly for fast iteration and experimentation, while DL models require longer training times due to complex, multi-layered architectures. So training cost, infrastructure, energy and complexity are higher with DL, but ML may not perform for large-scale problems.

Interpretability and Transparency

Other factors to consider when comparing machine learning and deep learning are interpretability (how easily a human can understand why a model made a prediction) and transparency (how visible and explainable the model’s internal logic and decision process are).

ML models are designed to be transparent and often more interpretable, showing feature importance, allowing step-by-step reasoning. For example: The if-then rules of decision trees are human-readable: linear regression coefficients show direct feature impact, and the odds ratios of linear regression explain influence.

DL models act more like "black boxes" from a transparency standpoint. They don’t rely on explicit rules or human-designed features. They contain millions of parameters, and learn hierarchical, distributed representations, making it difficult to understand which features cause a prediction.

Interpretability is important for auditing and becomes critical in regulated industries such as healthcare, finance and legal where high-stakes decisions are made routinely and trust is essential.

When to Use Machine Learning

General guidance is to use ML when a well-defined problem involves patterns in data that are hard to define with fixed rules, but where deep learning would be unnecessary or inefficient. ML is well suited when the data is structured and the dataset is small–medium-sized, as with business data (sales forecasting, financial metrics, customer records).

ML is effective when the compute budget is limited and fast iteration matters (fraud detection, credit scoring), and for applications where interpretability and explainability are required (finance, healthcare, insurance, legal).

When to Use Deep Learning

DL can excel at problems that involve complex patterns in large amounts of diverse, unstructured data, when you have GPUs/TPUs available and the time to support it. DL is best suited for inputs that are difficult to model with traditional ML (images, video, audio). DL is needed when manual feature design is difficult or impossible but raw data contains useful signals. DL is also appropriate when accuracy is more important than interpretability and cost and the system can tolerate longer training cycles.

DL is especially effective when transfer learning is available from pretrained models (image and object recognition) and the problem involves perception or language (computer vision, speech recognition, natural language processing, autonomous vehicles and robotics).

Real-World AI Examples

Is ChatGPT AI or ML? The answer is, yes!

Remember that ML and DL are both types of AI, and DL is a subset of ML. Actually, ChatGPT is a deep learning model built with a very large transformer neural network. GPT (Generative Pre-trained Transformer) is layered with millions to billions of parameters and massive amounts of training data.

Popular image creation systems like DALL-E and Midjourney are diffusion models built using deep neural networks, so both fit into the DL category. Both require large-scale training to create images from text prompts, intensive computation and representation learning.

When Netflix or Spotify make recommendations they use a combination of traditional ML models and DL models working together. These systems analyze user behavior, content attributes and similarities across both to decide what content to show, in what order, to which users. ML is used for ranking, personalization and A/B testing. DL is used for modeling user taste, understanding content and learning user-item relationships at scale.

These products look like this in the AI system hierarchy:

Artificial Intelligence (AI)

 └── Machine Learning (ML)

       └── Collaborative filtering models (Netflix/Spotify)

 └── Deep Learning (DL)

       └── Diffusion models (DALL·E, Midjourney)

       └── Transformer models (ChatGPT/GPT, Netflix/Spotify)

Choosing the Right Approach: A Decision Checklist

Dataset size:
Small/structured = ML
Large/unstructured = DL

Need for interpretability
High = ML
Low = DL is acceptable

Available computational resources
Limited = ML
Robust = DL is possible

Problem type
Tabular data = ML
Images/text/audio = DL

Learning Roadmaps for ML vs DL

Here’s a practical learning roadmap, starting with some shared fundamentals, since DL builds on ML fundamentals. Also keep in mind that your specific path depends on the particular problem to solve and the available resources for your system.

Shared fundamentals:

• Learn basic programming and data prep like Python fundamentals, NumPy, Polars/pandas and data visualization (matplotlib, seaborn)
• Know math fundamentals such as linear algebra, probability and statistics and basic calculus
• Learn data handling basics like data cleaning, feature engineering, training, validation and testing

Machine Learning path:

• Core concepts such as supervised vs unsupervised learning, bias-variance tradeoff, overfitting and regularization and evaluation metrics.
• Focus on classic ML models (linear and logistic regression, decision trees, random forests, SVMs).
• Core libraries (scikit-learn)
• Feature engineering, including encoding categorical variables, scaling and normalization, time-based features and aggregations.
• Model tuning and validation techniques such as cross-validation, hyperparameter tuning, feature selection and error analysis.
• Production ML tasks, including model deployment, monitoring and drift detection, retraining pipelines and explainability.

Deep Learning path:

• Neural network fundamentals, including perceptron, activation functions, loss functions, backpropagation and optimization
• Core DL architectures with a focus on feedforward networks, CNNs (images), RNNs/LSTMs/GRUs (sequences) and transformers (NLP, vision)
• DL Frameworks (Pytorch, TensorFlow, Keras)
• Training (GPU training, distributed training, mixed precision and transfer learning)

Remember that DL builds on ML fundamentals, so start with ML basics regardless of your end goal.

Making the Right Choice for Your Needs

Machine learning and deep learning are two approaches to achieving AI, depending on your data requirements, computational demands, interpretability needs and use cases.

ML use cases are typified by smaller, tabular structured datasets. They often have high interpretability/explainability needs and have lower computational requirements and time commitments.

DL use cases involve complex patterns, and large amounts of diverse, unstructured data and accuracy is more important than interpretability. A much larger compute infrastructure and time investment is needed for training DL models.

The best choice depends on your specific problem and available resources. Know that both technologies continue to evolve, with more robust model architectures using less memory, more efficient training and better evaluation and testing. There is growing convergence in AI where ML, DL and rules are combined in hybrid systems. New applications and regulatory and governance demands will also influence how models are built and deployed.

ML is not replacing DL. Both continue to evolve side by side.