3D fighting games are a variation of the popular fighting game genre. Besides the obvious graphical difference, 3D fighters tend to have slower animations, thus slower game mechanics. You can't use combos and do quick moves. You have to see the animation play out. Despite this, 3D fighters are not inferior to 2D fighting games - they're just in a slightly different ballpark.
Besides this, there is also the innovative side-step ability. Side stepping keeps the camera in a 2D plane perspective, while one of the characters move. With this, appears that the stage revolves, when it's really just the camera moving to keep the two fighters in the same position. Side stepping is used for executing new moves, or as an effective dodge.