loginid vs. uid.

[Jesse W. Asher]

I have learned to make a distinction between a loginid and the userid.
The loginid is the actual name of your login.  For example:  jessea.
The userid is the actual number, your uid.  For example:  110.

I consider these two separate concepts - one is a name and the other a
number and they are not interchangeable.

My question is does anyone else view them this way, and if not what is
the relationship?  The reason I make this distinction is because your
uid can be changed while your loginid doesn't have to be changed - the
os looks at your uid (the number) to determine who your are in most
cases.  An example is su changing your uid to 0 (or to whatever your su
uid is) while leaving your login intact.  Of course you can have both
changed, but the above leaves me to believe that they are not
interchangeable concepts.  The uid is not the same as the loginid.
Does anyone have any comments on this?