And some compact size 1911s have 3.5" barrels.
It's hard for me to keep all the different variations seperate. Commander, officer, etc is basically Colt terminology. Look at models from other manufacturers and you'll get different names for essentially the same things.
Government = full size frame, full size slide
Commander = full size frame, shorter slide and barrel
Officer = smaller frame, shorter slide and barrel
I know that's pretty generic, but it works for me. I don't have to worry about 5" barrels, 4" barrels, 4.25" barrels, 3.5" barrels, etc.