I've been learning guitar for a couple of years (being already an experienced pianist), and it was very surprising to me how many different techniques need to be mastered to play guitar. I never got to the level on piano where the precise way I hit the keys mattered (apart from soft or loud). On a guitar how precisely you hold and move your fingers makes a massive difference. Hammer-on, pull-off, bends, slides, barring and holding down multiple strings with one finger, are all different techniques. Then there's exactly where you hold the finger in relation to the fret which can really change the sound (or in my case, be completely wrong). On your right hand, there's how you pick or strum, even whether you use a plectrum, the pads of your fingers, or your nails.