In a sense you are both correct. You are correct because they are both decendent from the same set of dogs. The AmStaf is a decendent of the same gene pool as a true APBT, the only difference is in the registration. The AKC does not recognize “Pit Bulls” as being a specific breed. The AmStaf is very similar, though more selectively bred and with SLIGHTLY different breed standads. Howeve, AmStafs can, in fact, be double registered with other registries, such as the United Kennel Club, AS PITS, but Pits (even if they are pure bred and have papers from another registry,) can not be reistered with the AKC as AmStafs. They are essentially the same genetically though. The owners and breeders of AmStafs would argue that thier breed is different than an APBT because they have different breed standards, but, for anybody but those showing AmStafs, that’s just a formality. I guess, in the long run, all dog breeds have worked the same though; they are selectively bred until they are genetically different from the breed from whence they orriginated. So, who knows, maybe in the future AmStafs will be a very unique and separate breed from APBTs’. But, leaning to your side, I do not believe that is currently the case. Currently, both breeds are decendents from the same gene pool and there is not enough difference genetically for them to be considered entirely separate from one another. Most of the difference lies in how their parents were registered. In fact, the AKC didn’t even recognize a difference up untill 1936. On the other end of the argument, both the APBT and AmStafs are very different from their English cousins, the Staffordshire Bull Terrier.
