5.00 m33-6 vs 6.60 PRO-B9

What does 6.60 PRO-B9 do that m33 dosen't?

I recently hacked a PSPgo for a friend using the 6.20 PRO-B9. I noticed that it wanted to use something called the infernal iso engine. So I was wondering, what does the newer CFW bring to the table besides the obvious ability to play newer games without a patch?