Well, if I look at its WP description:
Nix is a cross-platform package manager that utilizes a purely functional
deployment model where software is installed into unique directories generated
through cryptographic hashes. It is also the name of the tool's programming
language. A package's hash takes into account the dependencies, which is claimed
to eliminate dependency hell.This package management model advertises more
reliable, reproducible, and portable packages.
There are so many words there that people get fanatical about.