American Bulldog Question

For one thing, a pure american bulldog will have an underbite,a pit bull won't.

american bulldogs have what looks like black lip liner on, you will notice their hair/coat is softer where a pitbull tends to be more wirey/waxy in comparison, bulldogs tend to have the patches of color over the eye(s) and a bulldogs tail tends to look like the letter "c" where a pitbull has a straight tail. Also remember that there are two different types of bulldogs. hope it helps!