Walmart has both Pork Shoulder Picnic Roast and Pork Shoulder Butt Roast, What's the difference? The picnic is 1.18/lb and the Butt is 1.78/lb. I'm leaning towards purchasing 2-3 of these and I'm thinking about going with the Butts using simple logic of you get what you pay for. Is there really much of a diffence between the two? Are these prices fair?