Powerbuilding essentially refers to bodybuilders that drive their hypertrophy through some sort of strength training or through progressive overload via increasing rep range or weight. Guys that commonly use this term might train with linear periodiazation, like western periodization, or they might do something like HIT or DC Training. Again, remember that in bodybuilding the primary objective is muscle size and symmetry, whereas in powerlifting it's the numbers you put up. Therefore, the strength is just a means to an end for the powerbuilder, whereas for the powerlifter strength is the end in itself.