So many official Microsoft comments about these things!
Not all of them backwards-compatible with each other.
Friend-of-the-site Superannuation suggested that someone make a chart about it. Good idea, we told Superannuation, but how about you do it?
When you see it all laid out, it kind of helps, yes? The pieces almost fit!
Note: The people behind the PlayStation 4 have been keeping quiet about just how offline-friendly and used-game-friendly their new console will be. Perhaps that's because they saw what happened when their Xbox One rivals got chatty.
Really, all we wanted were answers that made sense and were consistent. Bring on E3!