Instead of "pro" and "amateur" (or "Home player"), I've always categorized players as "advanced", "beginner", or somewhere in between.

The term "pro", as Gary says above, simply means a person (or player) who is paid for his performance.

Some "pros" aren't even advanced players, but, due to a combination of "entertainer" skills, and, either being able to play enough good basic chords in one key (and use the transposer), or use SMF for most of the performance, they certainly manage to get paid (and sometimes very well) for their work and are quite successful.

I also know many "home players" who are incredibly talented and are monster players, but just don't want to perform in public or make performing their means of making money.

Ian