Technically speaking however they are in fact finishes sorry I didnt realize I needed to be so darn selective in how I say things....
Actually, as I understand it, the term "finish" when used with guns, is an
applied coating of some sort. And the stainless CZ guns don't have that. So, technically they aren't finishes.
EAA/Witness calls one of their finishes "Wonder Finish", but make it clear, when discussing that WONDER "finish," that it isn't really a finish at all, but a treatment -- a hardening process. They differentiate between finishes and non-finishes.
The stainless CZ guns are available in three levels of polish: matte, low-luster, highly polished. The problem is finding them.
And as I wrote earlier, the two types of CZs being discussed come with
different features -- and whether you buy a stainless metal gun or nickel plated one will determine the features you get. There is more different in those guns than just the metal/finish.
Even the caliber changes the features a bit. That may end up being more important than how they look. Some have full-length guide rods, some don't, some have the extended rails, some don't, some have ambi-dextrous safeties and some don't; there are other differences.
You'll notice that the slide on the .40 CZ above has rails all the way to the end of the slide, while the 9mm above it doesn't. That .40 will have a full-length guide rod, and the 9mm won't. The .40 SA will, the 9mm SA won't; but beavertails on those models will be different, too.
The nickel finish probably resists minor scratches better than stainless, but stainless will be easier to repair if you get a bad boo-boo. (Not much you can do with the nickel finish if it's badly damaged. But I've never seen nor heard of that happening.)