Virtual Machines (VMs)

VMs are an abstraction of physical hardware turning one server into many servers. The hypervisor allows multiple VMs to run on a single machine.

Characteristics:

• Each VM includes a full copy of an operating system
• Heavyweight (GBs in size)
• Slower to start (minutes)
• Complete isolation
• More resource intensive

Containers

Containers are an abstraction at the app layer that packages code and dependencies together. Multiple containers can run on the same machine and share the OS kernel.

Characteristics:

• Share the host OS kernel
• Lightweight (MBs in size)
• Fast to start (seconds)
• Process-level isolation
• More efficient resource usage

When to Use Each

Use VMs when:

• You need complete isolation
• Running different operating systems
• Legacy applications requiring specific OS versions

Use Containers when:

• You need portability and consistency
• Microservices architecture
• Rapid scaling and deployment
• Development and testing environments