Real Fury Fatal Bout

Could someone clarify to me a few things about Fatal Fury?

What are the differences of, for example, Fatal Fury 2 and Real Bout Fatal Fury 2 or Fatal Fury Special and Real Bout Fatal Fury Special? Are they totally different games or are they just named differently?

Totally different. Fatal Fury Special is a tweaked version of Fatal Fury 2 with a few adjustments to the gameplay and a few more backgrounds and playable characters added.

Real Bout 2, is similar to Real Bout Special, but the engine is reworked, a lot of moves and combos are changed or removed and has 3 more playable characters (Geese makes 4 if you have MVS without unibios, and wouldn't be playable in RBS).

In case this is your next question, the order the games were released is:

Fatal Fury
Fatal Fury 2
Fatal Fury Special
Fatal Fury 3

Real Bout Fatal Fury
Real Bout Special
Real Bout 2: the Newcomers

Garou: Mark of the Wolves

Thanks!

They're games with about a 5-6 years gap between them.

They're all worth the bucks anyway.