Sorry, I don't understand what the difference is in the case of MacOS?

It is the same for any OS. Virtual machine boots a separate instance of the whole OS. This is slow, this is often too much isolated (you can't easily/effectively share files between host and guest), you need to set artificial limits on VM disk/memory/cpu. On the other side, containers work in the context of host OS, what means less overhead and easier interaction with host.

I see! Thank you! :)