What the difference between the three different WOWs?
That’s not enough information to know what you’re specifically asking about.
Name names. What “three different WoWs”?
World of Warcraft. Classic and hardcore
Where are you seeing these? Because that exact combination of labels doesn’t appear anywhere precisely like that.
WoW baseline, which is refered to as Retail WoW is the modern and current game version
Classic is an older version of the game
Hardcore is class but with the caveat of you only have one life; once you die your character on those realm are unplayable.