EC2 vs Lambda
Compare virtual machine-based compute with serverless function execution in AWS.
Compute
Amazon EC2
Amazon EC2 provides virtual machines in AWS with full control over the operating system, networking, installed software, and runtime behavior. It is commonly used for long-running services, custom environments, and workloads that need host-level flexibility.
Compute
AWS Lambda
AWS Lambda is a serverless compute service that runs code in response to events without requiring server management. It is optimized for event-driven, short-lived, and highly elastic workloads.
Key Differences
EC2 gives you full VM-level control, while Lambda abstracts away server management completely.
EC2 is suitable for long-running processes and custom environments, while Lambda is designed for short-lived event-driven execution.
With EC2 you manage patching, scaling, and instance lifecycle, while Lambda handles scaling and infrastructure automatically.
Lambda has runtime and execution model constraints, while EC2 gives much more freedom over runtime behavior.
EC2 is better when you need predictable server-level control, while Lambda is better when you want minimal operational overhead.
Lambda fits serverless architectures, while EC2 fits traditional or hybrid infrastructure-centric architectures.
When to Use
When to use EC2
Use EC2 when you need full operating system access, custom software stacks, long-running services, background workers, or workloads that do not fit serverless execution limits well.
When to use Lambda
Use Lambda when workloads are event-driven, bursty, short-lived, and you want automatic scaling without managing servers.
Tradeoffs
EC2 offers flexibility and control, but requires much more infrastructure management.
Lambda reduces operational burden and scales easily, but imposes constraints on runtime model, execution duration, and architecture.
EC2 is stronger for infrastructure control, while Lambda is stronger for serverless speed and simplicity.
Common Mistakes
Choosing Lambda for workloads that are long-running or heavily dependent on custom host behavior.
Choosing EC2 by default for small event-driven jobs that fit Lambda naturally.
Ignoring operational overhead differences when comparing compute options.
Interview Tip
The clean short answer is: EC2 gives server control, Lambda gives serverless execution.