The older Power Point is well documented in the Ammo Faq, tacked above.
The newer Power Point Plus is moly coated and tends to fragment abit more than the older PP, which IIRC has abit thicker jacket than the newer PP Plus.
YMMV, but having shot both factory offerings, I find the older PP to be more to my liking and my reloads tend to hold tighter groups than the factory fodder.
NOTE: this is one reason I prefer M4 "ramped" style uppers, when using these types of lead nosed bullets; in that the feed-ramps are far less likely to cause the bullet to "set-back" or hang-up when feeding from the magazine to the chamber. I get far more reliable feeding w/ "ramped" uppers.
Mike
ETA - seems I was thinkin you were asking the difference between the 2 PP rounds, which I described above, however IF your asking about the Winny 55grn spitzer type soft nose in relation to the rounds mentioned above, I'd say the main difference would be the weights; 55grn vs 64grn......, sorry for the misunderstanding