I'll save you the trouble of looking it up. The only difference is a bit more precision, one dot more, and 10 yards difference per club. The 10 yds / club is a big difference and worth it IMO. Some have said the longer Rapture Pro Irons ( 3I/4I) have a higher trajectory and land softer than the others. I cannot attest to that either way, but it might be related to which ball is used.
The real benefit is its the best way to increase distance at the same, slower, meter speed.
I debated upgrading to the Pro Rapture irons for a couple of weeks. But playing against the Pro Raptures and seeing what clubs they were hitting to some of the par 3's made me decide to go ahead and get them.
Hoping to see some Rapture Master Irons and Woods with steel shafts soon (Hint, hint WGT) with an increase in precision and distance.