The 50 and 70 are so alike that without having them side by side I couldnt really tell you their differences.
The 70 has more of a countoured grip than the 50, and there is soemthign different about the hammer on it aswell, but I cant remember what.
I good friend of mine owns a 50 and I own a 70.
I am extremely happy with my 70, its accurate, feels good in my hand, and is a heck of a pointer. All in All it has become my favorite pistol.
I have never had it jam on me once, and thats the honest truth, Altho It doesnt have more then 200 rounds through it in my possesion. It fed hollowpoints and hardball perfect, never had problems with either.
Very well made, I am one of the "If this were made today it would sell for so much just to cover manufacturing costs that it wouldnt be practical to buy." club. This i think is fairly true of the CZ 50 52 and 70 series.
As far as I know neither are in production today.