if I am the only user of my macpro, and I set it up 8 years ago, am I also the administrator? is the user and administrator the same

Probably...

You can confirm that on Users & Groups (Apple menu  > System Preferences, then click Users & Groups). There should be a tag right under your current username if you are the administrator.

Go to Apple menu > System Preferences > Users & Groups and look at your user name in the left sidebar. It will say Admin under your name if you are an Administrator.