A whole pork shoulder is typically cut into two roasts-- the butt and the picnic. Butts are often cut in half to yield even smaller roasts in the 3-4 lb. range. Picnics are typically cheaper than butts, per pound, but the yield is somewhat less, due to the larger upper leg bone contained therein, and a large fat cap. Picnics also typically come skin-on on the fat cap side, and barbecuers usually remove it and the fat cap to maximize surface area for rub and smoke. The muscles in the picnic differ from those in a butt, and lead some to characterize finished picnic meat as "drier" than that of the butt, probably to do with less intramuscular fat.