Around here rules varry track to track. It used to be the late models were the ones that looked like...well, late models and Street stock/hobby stock were stock bodied cars that were modified..then they started looking just like a late model( tube chassis car) only they were technically a camaro or whatever because they had the GM frame clip welded in. Now the LATE MODELS are the tube frame aluminum motor big $$$ cars and the street stocks are the ones that look like a late model,but have a frame clip, and the "bombers" are the stock framed cars with production bodies and claimer rules on the engine etc...
P.S. The street stocks are still big $$$ and the bombers are far from what the class was intended to be( cheap and affordable)....they use dart heads, direct drive trans etc. Like any class rules are pushed to the limit and beyond.Claim on a motor is 1500 and your motor or you can claim just their heads for 500 and your heads...the guys IKNOW that run this class have almost 2 grand in their heads.( must be cast iron) It's just an unwritten rule nobody claims someone elses motor(usually)