Wiener Schnitzel, for me, is veal only and I like to think that Jägerschnitzel is any meat used in the same way that's not veal. It makes sense to me seeing as it means "Hunter's cutlet". You really don't hunt for veal.
Although it's really the sauce that helps differentiate; I like a mushroom and onion sauce for Jägerschnitzel but I also make a caper-lemon cream sauce. I'm thinking that's more like extreme northern Italy/Austria but not sure.
I usually use pork, pounded flat and then flour, egg and panko. I like lard for the cooking fat.