Docker executor vs Running a docker container in machine executor

Hi,
I’m looking to find the differences between running a docker executor vs running a container in a machine executor. From this doc, we get:

if you require low-level access to the network or need to mount external volumes, consider using machine.

So like how is setup/privileges different between these 2 containers: where one container is the one spun up by docker executor, while the other is spun up via docker run in a machine executor