Using a piano keyboard as a computer keyboard (stackoverflow.com)

I think the key thing (pun intended) is that the piano is large and therefore people using it move their hands to accommodate, whereas a keyboard is small enough to reach all the relevant parts while not moving your hands but instead stretching the fingers/twisting the wrist, which is great for maximizing typing speed but not for minimizing RSI. It's been pet theory of mine for a while that the reason I don't have RSI despite typing a lot every day is that my technique is absolutely horrendous; I never learned to type properly, so I move my hands a bit while typing and don't always use the same finger for the same key, depending on the surrounding letters, which makes me a relatively slow typer (although not as much as you might think!) but seems to have prevented me from ever getting RSI.

Form is very different, as are the scale and type of movements.