there is a difference. a short shifter knob, only reduces the hieght of the knob and not the actual shift distance.
the short shift kit (SSK), aka short shifter, reduces the actual throw distance when you shift. some of the SSK also will reduce the hieght of the shift knob. I dont know too much about the B&M, so i cant comment on it. I did how ever have a UUC in past audi's. they were great.