We'll spell out the differences for each account, as needed.) Also, sometimes legality prevents a service from deleting everything you've posted publicly in the past, so remnants of your time there could remain in perpetuity.
This list includes the big-name sites most people use.
That's a tool more people should take advantage of. It will not delete a You Tube channel associated with the profile.
Naturally, "some data will be kept, and some data will be deleted or converted," according to Google.
This is the way to get rid of some accounts within Google.