How does Group Policy User Config know which User to apply to ?

I'm sure this is likely a really dumb question but I can't seem to find a clear answer.

I have minimal experience with Group Policy (last 10 years or so has largely been MDM (mobile device management) in the cloud with Apple and Android.. so I don't deal with Group Policy much at all. )

I understand there are 2 parts to a Group Policy

• Computer Configuration

• User Configuration

It makes sense to me that the "Computer Configuration" applies to the entire computer (as long as the Computer Object in AD is moved into the same location as the Group Policy)

But how does User Configuration work ?.. there's a particular Group Policy I've been editing and testing. I see it applying correctly to the AD User account I'm logging in as,. but that AD User Object is not in the Group Policy OU with the 4 Computer accounts. It's in an entirely different AD OU.. so how does the Group Policy know it applies to that 1 specific User ? (or does it apply to any Domain User that logs onto those 4 machines ?

Also.. does "User Configuration" NOT apply to Admin accounts ? (it doesn't seem to when I test)

UPDATE:.. I Googled for where to find "Loopback".. and sure enough, Loopback is enabled for this particular GPO. So I think that helps me understand how it applies to the Users I'm logging in as. (these 2 specific User Accounts, have "Logon TO..." list of only these 4 computers.. so it helps isolate security and GPO settings to just these 4 computers and only these 2 User accounts.

I felt like when I logged in as an Admin, I did not get User Config settings.. but I may be mistaken on that. (I guess I thought User Config GPO settings only applied to non-admins, but maybe I'm wrong about that)