Some one correct me if I'm wrong but here goes...
All Colt civy semi Ar 15's are refered to as "Sporters".
1. The older models are marked SP 1, had triangle hand guards and 1 in 12 barrels.
2. Transition models are marked Sporter II, when they went to 1 in 7 barrels and round hand guards.
3. Later models are marked just Sporter whether:
a. the model is a Competition, Match, Carbine etc.
b. the barrel twist is 1 in 7 or 1 in 9
4. I haven't seen any 2001 or later production to see whats stamped on them.
The term " regular Colt AR 15 " in the old days applied to the standard 20", 1 in 12, full stock model SP 1. Now days Colt makes quite a few different models.
Hope this helps.