Here are a few basic items sportsman has 8 inch tires , Late Model has 10 inch
Sportsman has stock frame LM is fabricated
suspension is almost stock on the sportsman LM has coil overs panhard bar ect
engine rules etc I bet you could build 2 or 3 good sportsman for what a LM cost
If you have a few min to kill here are the track rules for all 4 classes at our local track