What is the difference between the 12 oz gloves used in boxing, 4 oz gloves used in MMA, and bare fists in street brawls in terms of punching? Science says that power output for all these are extremely similar, but the effect they have on a person is much much different.
While either one of these glove sizes can do serious damage, the smaller the glove, the more damage it can do. A larger glove means more surface area, which means the force is more spread out. This would mean the receiver is less likely to get knocked out, but will still suffer cumulative brain damage long term. With a smaller glove, all the force is concentrated onto a single point. If the point is next to a vulnerable spot that gives good leverage for rocking the head such as the jaw or chin, it can lead to a devastating knockout. In addition, smaller gloves give more exposure to the knuckles.