Can anyone run through the main differences between the Easy, Medium, and Nightmare difficulties?

damage levels, enemy health and volume

Dying often, dying very often, dying all too often. :D

I personally never managed to beat the game on normal - always took the "easy" path in Undying. Once I've tried on normal but ended right in the middle of the game. Am I the only one thinking everything else than "easy" is way to brutal in this game?

No, you are not. In fact, it's a testament of how great this game is even though because of the low difficulty at Easy (although since it's old it's not like today "Easy") and those Howlers are so creepy and still tough because of the camera effect when they hit you (at first I was annoyed then I realized it's very unique)

Ok, then I don't have to feel too embarassed... The Howlers are little bastards even on easy, they are by far my most feared enemies in this game, they are so terribly fast and aggressive.

btw I've been in your lovely country last week. You sure have fine ladies up in the north!