Even weapons such as long sword (in-game vernacular. The weapons called long swords in the real world were closer to the in-game bastard swords) bastard sword, short sword, and great sword had a variety of styles based on each weapon, depending on the school studied under (though geographic regions tended to be similar enough for generalities to be made in modern times about "German-style" versus "Italian-style", etc.)
As far as those different styles granting different mechanical benefits, that's a tougher question, as the differences tend to be more subtle and don't really translate into "this one is +1 damage or this one is +1 to AC." Feats like Power Attack and Combat Expertise already cover a lot of the fiddly bits gained from one style over another.
Of course, it's possible to create feats for specific techniques, be it iaijitsu strikes, or half-swording or using the "Mordhau" grip from German styles where you use the blade as the handle and clobber your opponent with the pommel or quillions. Or possibly create a group of related technique feats that chain together to form a style.
