Bigger bore, intakes and trasnfers. They need ALOT more case work over a cheetah to fit the 78mm bore pistons. They use the CR500 style intakes as compared to the CR250's all though some of the smaller mil DM's still use the CR250 style with intake adapters.
A cub uses all stock componets. Stock head, Reeds, pipes.. None of these will fit on a DM or cheetah hence the term Cheetah cub.
The Cheetah use bigger reeds/intakes, different head and bigger flange on the exhaust. and the bore goes up to 73mm compared to the 68mm. Although I think I have heard of some 74mm cheetahs out there.
In short.. The Cheetah DM (Dominate Male) goes even further then the cheetah with a 78mm bore, bigger reeds/intakes, and bigger exhaust flanges if the builder prefers as the exhaust flanges are removeable.
Then you have the Cheetah DMX wich is a 85mm bore.