Domain User Vs. Local Admin User

Hi,

This is the first time I am posting a thread and its quite foolish. I want to know what is the difference between a Domain User ID added to Local Admins group and New User created in Local Admins Group ?

I know that there is no difference between the two scenarios, but just wanted a second opinion to prove it to one of the Users in my company. He is a software developer and insists that he should have local admin rights and that too with the administrator ID only, else he cannot work. My argument is that if his domain ID is added to the local admins group of his PC, then he can work in the same way as he would work when logged on as administrator of the same local PC.

Please help, and thanx for any help you people might give.