The pork shoulder picnic is the musculature providing the locomotion to the hog in the front leg, whereas the butt is above it, more in supporting the head and the shoulder blade and isn't worked anywhere near as much. The shoulder picnic is much leaner with far less marbling throughout because of its strenuous daily workouts and that makes it dryer when cooked, and conversely a stronger flavor to the meat because of the leanness. The shoulder butt has much greater fat dispersion and marbling, and fat is an acronym.. Flavor And Tenderness!
Great job on the butt!
BTW, Frank Zamboni came from Watertown, NY (my home town), the inventor of the Zamboni! As asked above, any relation?