The number of inuts & outputs are the same.

The biggest differences that I am aware of are that the A frame does not have resizers on the keyers and the G frame does; and the A frame will only go up to somewhere around either 7.x or 9.x software, while the G can go up higher - probably not to the v14 or v5 that the X frames can, but higher (and therefore more flexible & more stable) than the A frame.

Not really a list, but here's a few things that I remember:

• The upgrade from the original MVS-8000 to the A frame had a lot to do with the physical size of the frame (I think the cards were stacked vertically rather than horizontally).  The original 8000 was almost half of a rack when including the DME and DCU.  I believe frame mem card capacity was also increased.
• Not long after the A frame was released, the DVS-9000 was also released.  This was a more economical SD/SDI solution, rather than the multi-format capable MVS switcher.  The 9000 also included 4 channels of DME in the switcher frame.
• The G frame required an upgrade to the processor in the SCU (if coming from a 9000), and added the funtionality of resizers.  The G frame release coinsided with 7.x and many menu enhancements.  I believe Multi Program 2 was added with the G, as well.
• The X frame being shown at NAB (in 2010?) was a major player in 3D infrastructure, mainly because of the additional inputs (200), outputs (100) and keyers (8).  I remember Bob Ennis demoing the 8000X with a 4MEs plus P/P, and a long line to see the 3D truck that was next to the Sony booth that year.