A) Third numbered installment in the Guitar Hero franchise (fourth including Guitar Hero Encore: Rocks the 80's). Unlike the previous games, which were developed by Harmonix, Guitar Hero III (henceforth GH3) was developed mainly by Activision in an attempt to ride on the success of the previous Guitar Hero games. GH3 features a soundtrack full of artists befitting of it's subtitle "Legends of Rock." Artists like "Die Toten Hosen," "Héroes del Silencio," and "Eric Johnson." GH3 also attempts to pull the player more into the story of the game through animated cutscenes. It also adds battles with famous guitarists like "Tom Morello" and "Slash," these battles are essetially glorified versus mode except that the AI controlled character never makes mistakes unless you use a power up. It should also be mentioned that the final battle against Lou (the devil) is basically impossible even on easier difficulties without play it multiple times and hoping that Lou gets the less deadly powerups. It also adds a new Co-op career mode with songs that cannot be unlocked in any other mode, this means that if you own the PS3 or Wii version of the game you must buy another copy of the game to get another controller so you can play through co-op career in order to play these songs. For those that played the Playstation 2 version of GH2, the third installment adds downloadable content (DLC) in the form of additional songs, most of which are piss-poor songs/bands which no one wants to play and all of which are horribly overpriced (about $2.50 per song or $6.50 for pack of three songs (song packs and individual songs are separate and a song that is available in a song pack is not available individually and vise versa)). DLC is only available on the XBox 360 and Playstation 3 versions of the game. Completely new to the franchise is online play, now you can face off against others online (provided you are playing the XBox 360 version as the PS3 and Wii online modes rarely work).
B) A rhythm game for people with no friends (compare to Rock Band: a rhythm game for people with friends)
A: Hey wanna come over and play Guitar Hero III with me?
B: Nah, me and some guys are gonna go play Rock Band. We're finally gonna hook it up to the internet to get some of the 60+ songs that have been released for DLC.