Medium (also known as Regular in Guitar Hero Live) is the middle difficulty in Guitar Hero (hence the name). The difficulty uses only the green, red, yellow, and blue fret buttons. In Guitar Hero Live, all buttons are used but there are less notes than Advanced difficulty.
Differences from Easy and HardEdit
Medium uses one more fret button than easy, which uses only the green, red, and yellow fret buttons; and one less than hard, which uses all five buttons. It also has more chords and hammer ons. It even has a few split chords in the more difficult songs. Medium is much less difficult than Hard, mainly because the orange fret button is introduced at Hard. Also, Hard has three note chords and more split chords. Medium also moves slightly faster than easy, and with more notes. Some people find it easier to strum long strings of a note or a chord by simply strumming to the correct beat, whereas in easy one must follow a restricted note pattern. This is true because Eighth notes are introduced on this level, whereas other notes are used on Easy. This is why some people say it is less awkward to play medium than Easy. Some might say that Medium is more "free" than Easy for those reasons. Also, while easy has a few hammer ons, if any, per song, medium really introduces them, with more complex songs having main riffs that involve hammer ons.
FCing for Hard and Expert Players Edit
On Medium, almost every song is Full Combo-able by an experienced Hard player or Expert player, generally because there are no Orange Notes, which make playing a song more complicated. One example being Cliffs of Dover from GH3. On Medium, almost any Expert and/or some Hard players can 100% and/or FC it. Some Expert and Hard players say that Medium moves so slowly that they would prefer to turn on hyperspeed to FC the songs.