Someone who knows more than me had to walk be thru this. I'm translating my understanding back into this posting, so I may not quite have it right.
What you're describing is an autheniticated logon. In the general case, it goes like this:
A user on machine A (userA), logs into machine B as userB. UserB owns and can manipulate files. UserA is impersonating userB thru the login, but userA does not own the files. They're owned by userB.
In this instance, that userA is an administrator provides a different level of authentication for impersonating userB, who also happens to be an adminstrator. But it is still an impersonation. The files are still owned by userB, and not by userA.
As it was explained to me.