Yes, the butt is simply the upper more meaty portion of the entire shoulder.

Jan, you have asked this question multiple times in slightly different ways. The consensus has been that while nothing is like the pork belly, the shoulder makes a decent substitute depending on the recipe.

Yes, though a pork butt will be even better. Both, though the names sound so different, are from the same cut of meat. The "butt' is higher up on the shoulder than the "shoulder."