Sorry, but a butt is not really the same as a "shoulder". Quick rundown:
A pork shoulder is a rather large cut of meat, starting out at about 12-14 lb, and about 2 ft long. It can then be broken down into two smaller cuts of meat, the "shoulder butt" and the "Shoulder Picnic." I have heard the shoulder butt also be referred to as a Boston butt, pork butt, blade roast, or shoulder roast, blade in. I have heard the shoulder picnic be called a picnic or cali roast. It's true that the bones, as well as the shape and the presence of skin are different between the two. As maybe stated, mentioned, most ppl tend to prefer the butt.
dmp