As in the title; in the pre-Ragnarok versions those were two different resistances (Vitality/Health leech), but I have yet to find an item that increases Health leech resistance, and I am in the fourth world (I started a new game).

I guess they combined those resistances? Or what?

Okay, I found an epic spear with the Health leech resistance. Also, I looked through the game's text files and they wanted to apply a corresponding resistance in the hero's stats, but apparently somehow that change didn't make it to the game.

That would be it.