We're basically talking about sympathetic magic here and a kind of poetic logic.But in a fantasy world that death energy is part of the physics of the world!
The distinctions here don't really work on the basis of different kinds of physics, they work on the understanding that there is physics and not physics.
If you apply a rigorous enough system to magic than it does end up feeling like a kind of alternative science (such as in Brandon Sanderson), but that's not really the case even in D&D. You might know a bunch of things necromancy can do, but you don't know all the set of things Necromacy could possibly do, and there's no set of rules written down anywhere. If I make a new spell, I might balance it in the game, but as regards to how effects happen, it's just what feels right in a kind of poetic way.