Picnic shoulder is a cut of pork that comes, as you might expect, from the shoulder area of the pig.
Since the "shoulder" of a pig is a leg, and pigs walk on all four legs, the picnic shoulder is a cut with muscles that get a lot of work. All that work of walking around gives the shoulder a lot of flavor; it also gives that cut what could be called a lot of texture. Without the proper cooking (see below) is can be tough, but the right cooking method will bring out its fabulous flavor in the most tender of ways.
Picnic Shoulder Versus Pork Shoulder
So what's the difference between picnic shoulder and pork shoulder? In short, not much. They are, theoretically the same, with slight variations in how they are cut in different parts of the country. One can be substituted for the other in recipes without worry.
Picnic Shoulder Versus Pork Butt
And how does pork butt play in? Those well-versed in the bizarre nature of the names of meat cuts will already know that pork butt is, in fact, from the shoulder, or front legs, of the pig.
(What comes from the back legs? Ham!)
Cuts labeled "pork shoulder" or "picnic shoulder" are from the thinner, triangle-shaped end of the shoulder whereas the "butt" is from the thicker, more intensely marbled end of the shoulder. As such, picnic shoulder is a bit better for cooking whole and slicing, while pork butt is perfect for making pulled pork and other recipes in which the meat is meant to fall apart.
That said, you can, if the selection at the butcher counter demands, use picnic shoulder, pork shoulder, and pork butt interchangeably in most recipes.
How to Cook Picnic Shoulder
Picnic shoulder also benefits from being cooked, still long and slow, whole and then served sliced, almost like a ham. Keep it covered and moist while it cooks for the best results. Serve it warm, at room temperature, or chilled and toted along on a picnic. Get it? Picnic shoulder? Perfect for slicing and serving picnic-style!
Note: Many styles and regional variations exist in butchery, so when in doubt, ask your butcher for specifics.