The fresh shoulder is
the entire front leg of the hog. It is normally divided into two
seperate cuts. The pork picnic is the lower half of the pork
shoulder (left side on the illustration) and the upper half being the
pork butt (right on the illustration). Both the pork
picnic and the pork butt are used in foodservice primarily for
making BBQ pulled pork.
pork picnic is sometimes processed as a slicing picnic used in place of
a boiled ham at a much lower price. It is many times mislabled as
a "picnic ham". To be called a ham it must come from the hind leg
of a hog.