My understanding is that the pit-bull and american staffordshire terrier are from the same stock but the breeds have become seperate over time. In the US some dogs are dual registered as both Pit Bulls and American staffies. I think that the Pit Bull peeps will accept dogs that are kennel club rego but not vice-versa.
There is also an American bulldog that is like a taller more athletic version of the English bulldog (which frankly has been bred to a kind of silly point).
There is also a Boston Terrier that is a lovely type of bull breed that is small and perky but they are quite rare in Australia

There's also the good ole aussie pig dog which is probably one of the only breeds that is still evolving - probably because they are actually bred to work and not recognised by any kennel club. Some of them are lovely some of them are dreadful.

They're all big gorgeous boofas lol.

ETA - There are some people breeding miniture bull terriers now. They are uber-cute. I wantz one.
ETA 2 - here is a picture of a mini and a standard for comparison.