The Animal is bigger, and stronger than a clone all day long. The Clone has the price on it's side though. For someone wanting a stock mild race motor the Animal is the way to go, you can ride them for ever, and they come stock making about 9hp.
The Animal still needs mods if you want more than 11hp from it.
While the Clone can be built up for $500 to make more power than a Animal.
If your going all out for max power the Animal comes with a forgue crank, stronger alloy block, taller deck, and more crankcase space that allows you to go bigger.