ABC Pyro is a single developing agent (pyro only) developer using sodium carbonate as an accelerator. It was used for many, many years as the standard film developer, until D-76 came along. It is still a standby for many today. It is famous for its intense staining. But it also has a reputation for short tray life and inconsistent results. (I know, it doesn't happen with everyone. But check Hutching's "Book of Pyro.") PMK, Rollo Pyro, and the related Kodak D-7 have two developing agents, metol and pyro. They also have better keeping properties, are easier to mix, and have good reputations for consistency (except D-7, which many place with ABC in that regard). The stain is a bit less, but it is still effective and is quite consistent. Rollo pyro was designed for good stability with rotary processors, which expose the developer to more air than others.
No, you don't generally use a metaborate prewet with ABC pyro.