Ok some definitions
It is all pork.
Rear leg is what "ham" is made from. It is not ham until it is cured. Country ham is dry cured in salt and then hung to dry. City ham in cured in a salt brine. Both can be smoked. Cut the ham into two parts give you a butt ham and a shank ham.
Pork butts come from the shoulder so pork butt, pork shoulder are the same also sometime called the collar. The lower part of the front leg is the picnic.
Country ribs are pork butt cut into strips, it can also be cured for bacon. Most pulled pork is from the pork butt and picnic.
Ham steaks, or pork steaks are pork butt cut into steak form.
Mike