Pogona Vitticeps, common name Inland Bearded Dragon, is the species most commonly kept in the U.S.
Pagona Henrylawsoni is a close cousin of the Inland Dragon, I've never seen one in the states...Australia has very tight restrictions on their native species and that particular species has not made it to the U.S. as of yet.
Its actually theorized that every bearded dragon alive in the US right now originates from a small group smuggled in from Australia in the late 70s.