AWS Lambda vs AWS Step Functions: What are the differences?

# AWS Lambda vs AWS Step Functions

In this comparison, we will highlight key differences between AWS Lambda and AWS Step Functions.

1. **Execution Model**: AWS Lambda is a serverless computing service that allows you to run code without provisioning or managing servers. It is event-driven and operates on a per-request basis, executing functions in response to events. On the other hand, AWS Step Functions are a serverless orchestrator that enables you to coordinate multiple AWS services into serverless workflows. Step Functions allow you to define complex state machines with different states and transitions between them.

2. **Scalability**: AWS Lambda automatically scales based on the number of incoming requests, meaning it can handle a large volume of requests simultaneously without manual intervention. In contrast, AWS Step Functions are designed for orchestration and coordination of AWS services rather than handling high request volumes directly. Step Functions focus on managing the flow of execution between different service integrations.

3. **Use Cases**: AWS Lambda is commonly used for event-driven applications, real-time file processing, and background processing tasks. It is ideal for running small, individual functions in response to triggers. AWS Step Functions, on the other hand, are best suited for coordinating multiple AWS services in a workflow, handling long-running processes, state management, and error handling within complex applications.

4. **State Management**: AWS Lambda functions are stateless, meaning they do not maintain any state between invocations unless external services like databases are used to store state. In contrast, AWS Step Functions provide built-in state management capabilities, allowing you to track the state of a workflow, handle retries, and manage checkpoints within the workflow execution.

5. **Error Handling**: AWS Lambda provides basic error handling through retries and logging, requiring you to implement custom error handling logic within your function code. On the other hand, AWS Step Functions offer built-in error handling features, such as catching and retrying failed steps, defining catch handlers for different error types, and transitioning to specific states based on errors.

6. **Cost Structure**: AWS Lambda operates on a pay-per-use pricing model where you are charged based on the number of requests and the duration of code execution. In comparison, AWS Step Functions have a different pricing structure based on state transitions and state machine executions, with additional costs for API calls and data processing within workflows.

In Summary, AWS Lambda is ideal for executing individual functions in response to events, while AWS Step Functions excel at orchestrating complex workflows involving multiple AWS services and managing state transitions efficiently.