Looking at Class A's

The different engine ratings would reflect different chassis years. Ford re-rated the V10 (or, perhaps more accurately, specified the ratings at a different RPM), I think for regulatory compliance reasons as emissions or noise testing or something is done at the rated power. The engine itself is physically unchanged, though there may be some associated tweaks to the ECU programming. I would not give the difference any real thought.

I think there is a significant change at the same time from the 5 speed to the 6 speed transmission, and the latter is an actual improvement.