P,
No, are we talking about the SQL Server side.
I thought you wanted to know who the "Server" sees you as.
If you use Trusted_Connection, then the System_User returns something like:
Doman\FirstName.LastName
Whereas, UserName returns what they logged in as, which could be like some
DB defined user group like 'Engineers".
I don't have a Server available, but there really are 4 "perceptions" of who
the Server thinks you are.
Need more info,
Wayne