Another, relatively well-known difference between the two is cant deficiency in curves.
For the non-railway-educated: "cant" is the tilt of tracks in curves, e.g. how much the outer rail is higher than the inner one. Cant obviously reduces the centrifugal forces acting on travellers. If the track is not tilted enough for to eliminate centrifugal forces completely at maximum permitted speed, then we have a cant deficiency -- which is the normal case, because we also have to consider when a train goes slow or stops at a signal in a curve.
However, in France, cant deficiency is generally much lower than in almost all other countries. So much so that there is little practical benefit for tilting trains -- which is why we don't see them there. *Lunatic*, n. One whose delusions are out of fashion.
For cant = superelevation itself, in Europe, the general limit is the same as in the US, 160 mm. It can be higher in France, and higher for slab track elsewhere. I thought it is significantly higher, but upon checking: