The Plus come with a lid, and a barrier for making a "bedroom" area at one end of the cage with, plus one ramp cover. If you don't want the extra bedroom area (I don't bother with it) or the lid/roof, go with the standard instead. I'm pretty sure you can buy the ramp covers separately, and you'll need one if you're joining the two cages unless you want to make your own. The ramps aren't safe for piggies to walk on unless they're covered.