What is the difference between a Docker container and a virtual machine?

A Docker container and a virtual machine (VM) differ in virtualization level and architecture:

• Virtual Machine emulates a complete hardware environment, including its own OS. Multiple VMs can run on a single physical server, each with its own OS. This requires more resources (CPU, RAM, disk).

• Docker Container uses OS-level virtualization — containers share the host OS kernel but are isolated from each other and the system. Containers are lighter and start faster because they do not require a separate OS to run.

Example:

• VM: runs a full Windows or Linux with its own kernel.
• Docker: runs an application with its dependencies in an isolated space, using the host kernel.

Summary:

• Containers are more lightweight and faster.
• VMs provide stronger isolation and can run different OSes.

This affects technology choice depending on the tasks and requirements for isolation and performance.