Layers of Operating System

Operating system has 2 layers: Kernel and Applications layer.

The kernel connects the applications and hardware.

The Difference

Docker virtualises the application layer of the operating system. It uses the kernel of the host as it does not have it’s own kernel.

On the other hand, a VM uses it’s own application layer and kernel. So, it virtualises complete operating system.

Features

Size:

Size of docker is lesser than size of VMs as it only virtualises one layer.

Speed:

Docker is faster than any VM.

Compatibility:

VM of any OS can on any OS host. It’s not the case in docker. For example, a linux based docker image may not run on a windows kernel for compatibility issues.