AWS Lambda vs EC2: Which One Should You Use in 2025?

AWS provides multiple compute options, but two of the most widely compared services are AWS Lambda and Amazon EC2. As businesses modernize their cloud strategies in 2025, choosing between Lambda and EC2 has become more critical than ever. Both services allow you to run applications on AWS, but they differ in cost, scalability, architecture, maintenance, and ideal use cases.

This guide provides a detailed comparison of AWS Lambda and EC2 to help you decide which solution fits your application needs in 2025.

Overview of AWS Lambda and EC2

What is AWS Lambda?

AWS Lambda is a serverless compute service that executes code in response to events without requiring you to manage servers. You pay only for the compute time consumed when your code runs.

Key characteristics:

• Serverless architecture

• Event-driven execution

• Automatic scaling

• Pay-per-execution billing

What is Amazon EC2?

Amazon Elastic Compute Cloud (EC2) provides virtual servers in the cloud where you manage the OS, runtime, scaling, and security. It offers full control over the infrastructure.

Key characteristics:

• Complete server control

• Customizable compute instances

• Long-running workloads supported

• Pay-per-hour or per-second billing

Feature Comparison: AWS Lambda vs EC2 (2025)

When to Use AWS Lambda in 2025

AWS Lambda is ideal for applications that need event-driven execution, high scalability, and minimal server maintenance. It supports modern cloud-native and microservice architectures.

Choose Lambda if your needs include:

1. Event-Driven Applications

Perfect for workloads triggered by events such as S3 uploads, API calls, IoT sensors, or DynamoDB streams.

2. Unpredictable or Spiky Traffic

Lambda automatically scales to handle sudden traffic surges without pre-provisioning capacity.

3. Cost-Efficiency for Intermittent Workloads

You only pay for execution time, making Lambda cost-effective for non-continuous workloads.

4. Microservices and API Backends

Ideal for distributed and loosely-coupled architectures using API Gateway and Lambda functions.

5. Quick Development and Deployment

Developers focus on code, not server setup, enabling faster releases and reduced DevOps overhead.

When to Use Amazon EC2 in 2025

EC2 is best when applications require full control over servers, specific OS-level configurations, or long-running persistent processing.

Choose EC2 if your needs include:

1. Long-Running Applications

Web servers, backend systems, game servers, and enterprise platforms that run 24/7 are better suited for EC2.

2. Custom Environments and Operating System Control

If your software requires specific OS changes, libraries, or drivers, EC2 provides full customization.

3. High-Performance and Resource-Intensive Workloads

Suitable for machine learning model hosting, big data, video processing, or compute-intensive analytics.

4. Traditional Monolithic Applications

Legacy systems not designed for serverless are easier to migrate to EC2 than to Lambda.

5. Consistent Performance with No Time Limits

Unlike Lambda, EC2 has no execution time restrictions and can handle continuous background tasks.

Cost Comparison in 2025

Cost is one of the biggest factors in choosing between Lambda and EC2.

AWS Lambda Costing

You pay only for:

• Number of requests

• Execution duration

• Allocated memory

Best for low-to-medium usage workloads.

EC2 Costing

You pay for uptime:

• On-Demand, Reserved, or Spot pricing

• Storage, bandwidth, and attached services

Best for high-throughput or continuous workloads.

Rule of thumb for 2025:
If your application runs 24/7 and uses high compute consistently, EC2 is cheaper.
If your traffic varies or usage is low-medium, Lambda is more cost-efficient.

Performance Considerations

AWS Lambda

• Cold starts can add latency

• Best for lightweight, stateless workloads

• Can now run containerized functions up to 10 GB memory and 6 vCPUs

EC2

• Predictable performance with dedicated compute

• Allows GPU instances for ML and AI workloads

• Suitable for persistent, stateful, or low-latency apps

Security and Maintenance

AWS Lambda handles security patches, scaling, and server updates automatically. You secure the code and IAM permissions.

EC2 requires managing:

• OS patching

• Firewall rules

• Scaling policies

• Monitoring and backups

Lambda is low-maintenance, while EC2 requires DevOps involvement.

Which One Should You Choose in 2025?

Use AWS Lambda if your application is:

• Event-driven

• API or microservice based

• Intermittent or spiky in traffic

• Designed for quick deployment with minimal ops

Use Amazon EC2 if your application:

• Is long-running or resource-heavy

• Requires server customization

• Runs legacy or monolithic architectures

• Needs guaranteed performance and full control

Conclusion

AWS Lambda and EC2 both provide powerful compute solutions, but they serve different needs. In 2025, most organizations use a hybrid approach: Lambda for serverless services and EC2 for persistent workloads or legacy systems. The best choice depends on your architecture, traffic patterns, performance demands, and operating model. By aligning your workload with the right compute model, you can optimize both cost and performance on AWS.