None (なし Nashi?) refers characters who haven't studied a martial art or combat sport, and or don't fight at all.
Brawling or street fighting refers to the lack of a fighting style, but the capability to still fight. While having little formal training, if any, street fighters have instead honed their ability fighting on the streets illegally. And since their are no rules in a street fight, they can use weapons, classic or improvised weapons. As well as dirty fighting techniques like eye gouging, eye poking, groin hits, temple hits, throat locks, and other potentially fatal moves.