Guitar Hero is a form of twitch-based game (https://en.wikipedia.org/wiki/Twitch_gameplay). Where a QTE would be "hit the F key as many times as you can in 5 seconds", guitar hero is "hit the F key exactly when it needs to be hit".

I'm generalizing though. Some QTEs are a form of twitch gameplay (in which they require the player to hit at the perfect time), but twitch gameplay is not a form of QTE. What does set QTEs apart is that they are not, in fact, the whole game but are a sudden change of gameplay style which is gone as fast as it arrived.