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EC2 vs ECS: Key Differences Between Amazon‘s Compute Options

Amazon Web Services (AWS) offers several services for deploying applications and workloads on the cloud. Two of the most popular options are Amazon Elastic Compute Cloud (EC2) and Amazon Elastic Container Service (ECS). At first glance, these may seem similar – but there are some important distinctions.

In this comprehensive guide, we’ll compare EC2 and ECS across several factors to help you determine the best service for your needs.

What is Amazon EC2?

Amazon Elastic Compute Cloud (EC2) provides scalable compute capacity using virtual machines running on AWS infrastructure. With EC2, you can launch as many or as few virtual servers as you need, configure security and networking settings, and manage storage.

EC2 instances can run various operating systems, including Windows, Linux, and more. There is a wide selection of hardware configuration options to choose from when launching EC2 instances.

EC2 enables you to scale up or down to handle changes in demand, paying only for the compute time you use. It is designed to make web-scale cloud computing easier by eliminating your need to invest in hardware up front.

What is Amazon ECS?

Amazon Elastic Container Service (ECS) is a highly scalable container management service that supports Docker containers. With ECS, you can run and scale containerized applications on AWS without having to worry about infrastructure management.

Instead of provisioning virtual machines like with EC2, ECS allows you to run containers. This makes it simple to deploy modern applications using containers and microservices.

ECS handles starting, stopping, and scheduling containers across a cluster of Amazon EC2 instances. This removes the need to configure and operate your own cluster management infrastructure. ECS integrates with services like Elastic Load Balancing for load distribution and auto scaling to dynamically adjust capacity as needed.

EC2 Offers Configurable VMs, ECS Manages Containers

The first major difference between EC2 and ECS is in their architecture. As mentioned above, EC2 lets you provision virtual machines and gives you full control to configure resources and operating systems within each VM. ECS on the other hand is a container management platform that allows you to deploy your applications packaged in Docker containers, without worrying about the infrastructure.

With ECS, you don’t have to configure VMs yourself. Instead, ECS manages clusters of EC2 instances for you, taking care of infrastructure management tasks so you can focus on your applications. This makes containerized apps quick and easy to deploy.

So in summary:

  • EC2: Provides configurable VMs
  • ECS: Manages clusters and infrastructure for containerized apps

Flexibility vs Focus on Containers

Related to the architectural differences, EC2 and ECS differ considerably in flexibility vs optimized support for containers:

  • EC2 offers far more flexibility in terms of operating systems, hardware selection, customization, etc. You have full control over your VM instances.
  • ECS is purpose-built for containerized applications. It streamlines deploying apps using Docker containers and microservices architectures.

So with EC2 you can fine-tune VM configurations to suit your needs, while ECS aims to make running containerized apps simple.

Scaling and Elasticity

Both EC2 and ECS provide high scalability and elasticity, enabling you to easily scale your resource usage up or down to match changes in demand. However, the mechanism and granularity of scaling differs:

EC2 Auto Scaling works by automatically launching new VM instances (or terminating instances) based on metrics like CPU utilization. So it scales out at the instance level.

ECS Auto Scaling allows you to specify parameters that automatically scale the number of tasks running in your ECS cluster. So ECS can rapidly scale your containers.

In addition, ECS simplifies running highly available containerized apps by spreading tasks across multiple Availability Zones. The elastic nature of containers along with cluster management makes scaleout smooth.

So in a nutshell:

  • EC2 scales by adding or removing VM instances
  • ECS scales at the container level for more granular control

Use Cases and Workloads

Due to the architectural differences between EC2 and ECS, they lend themselves to different use cases:

EC2 Use Cases

EC2 works well for:

  • General purpose applications that require access to OS resources
  • Custom applications with complex infra requirements
  • Anything requiring Windows or a particular Linux environment
  • Batch computing jobs
  • Building a VPC with custom networking

It offers infrastructure configuration options unavailable on other compute options like containers. The ability to optimize the OS and resources for your app make EC2 ideal for many enterprise workloads.

ECS Use Cases

ECS is purpose-built for:

  • Microservices and other containerized applications
  • Anything leveraging a Docker workflow (CI/CD pipelines etc)
  • Web apps built using common frameworks like Node, Java, PHP, Python etc
  • Mobile and gaming application backends
  • Streaming and big data analysis apps

The simplicity of deploying containers makes experimenting faster, and scaling painless. ECS significantly lowers the barrier for taking modern containerized applications into production.

In general, ECS suits modern applications using microservices, as well as use cases where rapid iteration and portability are vital. It’s beginner friendly but scales seamlessly to large workloads.

Resource Allocation Differences

There is a key difference between EC2 and ECS when it comes to how each option allocates compute resources.

With EC2, resources are allocated on a per VM basis. Each VM instance has dedicated CPU, memory, disk and network resources for launching your applications. You select the capacity by choosing an appropriate instance type for your workload when first launching the instance.

In contrast, ECS allocates resources at the container level. ECS handles scheduling containers within a cluster, sharing resources between containers running on the same EC2 instance under the hood. You define CPU and memory requirements in a task definition, and ECS places the containers appropriately.

This means resource allocation on ECS is more flexible, allowing more efficient sharing between containers compared to rigid VM boundaries. However, EC2 gives you finer control over dedicating exact resources to each application or workload if needed.

Pricing Comparison

Both EC2 and ECS offer pay-as-you-go pricing models. With EC2, you are billed per second or hour depending on which billing option you choose. With ECS, you pay based on the vCPU and memory resources consumed across the ECS cluster for your tasks and services.

Pricing considerations for each:

EC2 pricing factors:

  • Instance type
  • Instance purchasing option (on-demand, reserved etc)
  • AMI pricing
  • Data transfer charges
  • Extra features (elastic IPs, load balancing etc)

ECS pricing factors:

  • EC2 instances and their pricing
  • CPU/memory utilization by containers
  • EBS volume types
  • Load balancing usage if applicable

A major benefit of ECS’s pricing model is that multiple containers can share the vCPU/memory of a single EC2 instance. This allows higher efficiency and workload density vs. one container or application per VM instance.

Between the flexibility of EC2 and optimizations of ECS, you can strike the right balance of control and efficiency for your budget and needs.

Factors to Consider When Choosing

We’ve covered several key differences and tradeoffs between Amazon EC2 and Amazon ECS above. To recap, here are some of the factors to consider when deciding between EC2 and ECS:

Consider EC2 for:

  • Complete control over OS, hardware, configurations
  • Custom networking needs
  • Complex application dependencies
  • Running legacy apps or certain Windows workloads
  • Specialized batch computing

Consider Amazon ECS for:

  • Modern containerized applications
  • Microservices architectures
  • Quick iteration and continuous deployment needs
  • Running containerized apps with little effort
  • Cost or resource optimization

Other deciding factors:

  • Skillset of your team
  • Compliance requirements
  • App migration strategy or rewrite timeframe
  • Budget or cost optimization targets


Hopefully this detailed comparison has helped illustrate the pros and cons of Amazon Elastic Compute Cloud (EC2) and Amazon Elastic Container Service (ECS).

At a high level, EC2 offers flexible and customizable virtual machines, while ECS streamlines deploying and running containerized apps without infrastructure headaches. Both services enable effortless scale, and which route makes more sense comes down to your use case technical needs.

By evaluating the key points of differentiation around architecture, use cases, scaling, resource allocation and pricing models covered here, you should be well equipped to select the right AWS compute option for your next project!