I believe they are just Cavity vs. Muscleback blade models. I was looking at the '04 Rac TP's for a while. Those are sweet and one of a handful of iron sets I would switch out from the Miura's to attain. I think, for me, a CB 3-7 and MB 8-PW would be the best set.
Get 'em. If for no other reason, to make me jealous.
