Reptile & Amphibian Forums

I have been searching for a baby african bull frog (Pyxicephalus adspersus) aka: the big kind. I am not interested in the dwarfs, and I want a male. I called petco nearby and they said they had 2 "pixie frogs" I asked if they were Pyxicephalus adspersus and they said "We don't know, we just call them pixie frogs, is there a difference?" How can I differentiate between the giants and the dwarf species and how can I, at a young age, differ the sexes to find a male?

I don't know anything about african bull frogs. I don know that most pet stores, especially the national chains, don't know squat about what they have. I have seen a lot of mislabeled herps.
You have been warned.