Docker containers doesn’t need full blown operating system to work, thats what makes them light and easy to boot.
Hypervisor is a software that logically creates servers in one phyiscal machine. Each server has its own operating system. Booting time is low because its one full operating system for each server.
Image contains everything that your app needs to run. It contains OS, code. Images can be versioned, its called Snapshot.
Container is simply a running instance of an Image. Think of it as a blueprint.