Def Jam Rapstar (PS3) vs Green Day: Rock Band (PS3)

Def Jam Rapstar captures the essence of what Hip Hop is all about: the music, the battles and of course...the swagger.
The ultimate emcee experience for video game consoles, Def Jam Rapstar is the only music game that focuses exclusively on Hip Hop. With more than 40 of the greatest Hip Hop songs available at release, Def Jam Rapstar allows you to be the star: by rhyming, using your console camera, and uploading your video to the fully integrated Def Jam Rapstar community at www.defjamrapstar.com. Def Jam Rapstar also offers you the ability to freestyle over tracks by some of the hottest hip hop producers and upload your freestyle performances for the world to decide how good you really are.

Green Day: Rock Band is a music video game developed by Harmonix Music Systems, published by MTV Games and distributed by Electronic Arts. It is the fifth major console release in the Rock Band music video game series and, like other games in the series, it allows players to simulate the playing of rock music by using controllers shaped like musical instruments.
The game's soundtrack consists of songs by the popular punk rock group Green Day. Green Day: Rock Band will feature virtual depictions of the three band members performing the songs in new venues designed for the game. The game will incorporate existing Green Day songs already released for the Rock Band series as downloadable content, and will allow players to export its full tracklist to the other Rock Band game titles except The Beatles: Rock Band.