I think one other big difference is the grade. There is no part of the ascent on Hospitales that even comes close to the huffing-and-puffing part of the ascent from SJPP. Hospitales has a fairly steady, gradual ascent, which makes it, I think, a much easier walk than out of SJPP. (If you take the alternative route through Pola de Allande, though, you will have 400 more meters of elevation gain than you get on the Hospitales route, and a short but very steep ending to take you to the Puerto de Palo where the two routes combine).
And yes I also agree that the descent from Hospitales is much harsher than the descent to Roncesvalles.