Thanks for the masterclass suggestions! Yeah I can tell that there's something different in the way that Cyprien plays it, in terms of subtle changes in the tempo in the fast sections. I'll have to re-listen to it more carefully.
A lot of the changes in the Rubinstein version is in the left hand and in the dynamics. They affect the overall texture of the sound rather than the melody directly. I think this is most evident during the middle "slow" section where you'll hear some different notes, but it occurs during the fast section too (such as during the climax). For the ending section, the left hand is playing 8th notes in Fontana version, so it's 16ths vs 8ths, while in the Rubinstein version the left hand is playing triplets, so it continues with the 4 vs 3 polyrhythm of the fast section. This leads to a different textural feel; in the Fontana version, the left hand's thumb matches with the accent in the right hand, while in the Rubinstein version, the left hand's emphasizes the beat instead, which puts the syncopated right hand "melody" accents in sharper relief. Generally speaking, the Rubinstein version is somewhat harder than the Fontana version, and the texture is somewhat richer. I can put up an explanatory video if you want (i.e. playing sections of both versions slowly and without pedal) so you can hear the difference.
Incidentally, Cyprien's rendition I think has some unnecessary or gratuitous stuff, such as the left hand being overly accented in the recapitulation of the "fast" theme. While yes there are accents in the Rubinstein version (but not in the Fontana version), I think he carries this to the extreme, thus detracting from the overall feel of the piece. I try to do a more subtle accent, but not sure if it comes out well (and admittedly, am still working on adjusting just how much accent there should be).