@ MonekyBomb... There's a few basic differences but besides their jaw shape, their size and colour - Alligators are almost friendly. They'll move off if disturbed whereas Crocodiles are definitely not friendly, they'll attack you if you get too close and are extremely aggresive.

Here's a photograph taken at a local Game Park/Reserve of a Crocodile carrying a full grown Warthog in it's jaws. Just by looking at how much of the road this guy covers it gives a good idea of his size.