Certain mechanics have been either tweaked or phased out altogether.
Street Fighter IV’s Focus Attack is gone; no longer can you make the tactical decision to wind up damage-absorbent strikes that cause your opponent to crumple to the ground. Rounds can end with fancy (and often hilarious) environmental finishing animations. Furthermore, Super Combos have been removed to make way for a decidedly more interesting and character-specific system.
Enter the V-Gauge. As you land and take hits, it fills up. It fuels three specific abilities: V-Skills, V-Reversals, and V-Triggers. V-Skills are character-based special moves, but they all vary in offensive and defensive capabilities. For example, Bison’s involves reflecting projectile attacks, while Ryu hearkens back to Street Fighter III with his parrying ability. V-Reversals are the Street Fighter V equivalent of Combo Breakers; while you’re being attacked, you can launch a counter strike. If you fill the entire V-Gauge and decide to use it in one swoop, you can activate a V-Trigger, which is a variable power that can turn the tide of any battle.