This article is from the American Pit Bull Terriers Breed FAQ, by Michael Bur with numerous contributions by others.
Well, yes and no. How's that for straightforward? As stated in the
introduction, there are several different "breeds" of dogs that are
refered to as "Pit Bulls" by the general public. Primarily, these are
the American Pit Bull Terrier, the American Staffordshire Terrier, and
the Staffordshire Bull Terrier. There are two general schools of thought
pertaining to this issue. The first is that these dogs come from
the same English/Irish pit fighting stock of over 100 years ago but have
been subsequently bred to differing standards and are now different
breeds. The second is that these dogs are just different "strains"
(working vs. show) of the same breed. It all really comes down to
how one defines what constitutes a breed. In general, however, ASTs
have lost most of the gameness of their pit fighting ancestors, while
at least some well-bred lines of APBTs have maintained this quality
unaltered. Dogs of both breeds, if well-bred, have similar human-