Definitely piano. It's harder on the inside. That steel frame. And that's beyond the thickness of the wood casing. Isn't it walnut wood too for the frame?Whereas a violin... You could sit on that and crush it. Thin wood. Nothing on the inside.Pianos are harder than.... brass for sure, woodwinds... strings of course, like the violin. Bass might be hardest though of the strings. Most percussion... except for something like the glockenspiel with metal bars. Interesting that it's a keyboard instrument again.
Banjo is even harder
Show me an equivalent of Prokofiev's cadenza from pc2, where you have four octave large speed runs in one hand and giant leaps in the other. And that's just pressing the notes. I'm not even talking about the vast number of music composed for piano, sentimental works which are really difficult to play well, like Rach concerti. Piano is the ultimate instrument among all.
I doubt any of us here can play both of these instruments on a level high enough to even assess this question accurately.
Having played both at nearly the same level, I have no question in my mind that violin is harder.Intonation is a *** pregnant dogBowing is a *** pregnant dogviolin is *** pregnant dogviolin is pregnant dogis pregnant dogpregnant dog
Violin. And you have to play every single day for hours to be any good.