This is a list of the types of instruments in the Guitar Hero games.
Before Guitar Hero World Tour and also for the On Tour series
In Guitar Hero 1-3, the instruments are all real instruments by real guitar companies, as well as fake "special instruments". In On Tour, they are all instruments by Gibson. In On Tour Decades, they are all made up instruments with designs close to the instruments in On Tour.
Guitar Hero World Tour and newer games
Starting in GHWT, there are now customization for drums, microphones, guitar, and bass. All of them (except for drums) are fake made instruments (though some Guitars are designed simarily to real guitars). They must be bought (until GH5, when there is no money and everything, unlocked or not, is avalibele).In GH Metallica, Van Halen, and Aerosmith, they are all real guitars by the band. (In the case of GH Metallica and Van Halen, where it is also the drums, microphones, and basses of the band. In GH Metallica, you can still use the GHWT guitars.) In Gh5, all the Guitars, drums, and basses are real. And while only one microphone is real, and bass and guitar have some fake instruments, it's mostly real ones.