what is the difference between pork shoulder and pork sirloin?
Pork sirloin roasts lack the marbled fat associated with pork shoulder roasts. The rear loin of the pig is tougher and leaner, so while a pork sirloin roast is full of flavor, it can dry out quickly unless cooked properly. ... Arm picnic shoulder roasts are marbled as well, though less so than Boston butt shoulder roasts.