Though IGN says that the game is "mechanically identical" to its wicked AO twin, they said there are some more "cosmetic" changes. First off, the game's death strikes have been blurred and darkened to the point that the heinous act being done is unidentifiable. Like using a vending machine blindfolded, you just use a push a couple of buttons and hope that you get a Snickers. Though IGN says the kills are still fun, they say they're less rewarding in the still-not-particularly-family-friendly version.
There's something much more heinous in the changes though: You can no longer rip an enemy's testicles off with pliers. ... Hear that? It's the sound of Manhunt 2's GOTY award flying out the window. This is 2007! What's the point of even playing a game if you can't rip some testicles asunder? Oh, also: -1 to Manhunt 2 machinima.