Two clear examples off-the-bat I can think of is: 1. Nix installs all necessary libraries as well as part of the install path. That is - if you need two versio

Two clear examples off-the-bat I can think of is: 1. Nix installs all necessary libraries as well as part of the install path. That is - if you need two versions of a library, you aren't needing to contend with whatever is globally installed. I ran into this a lot with Python stuff, personally. 2. You can install different versions of the same software without needing dedicated version managers. This is immensely useful if you work on several different projects that might be using different versions of tooling. -- But that's just Nix the package manager. Brew does not solve problems of OS configuration, dotfiles management, reproducibility, etc., all of things Nix solves off-the-bat. For example, I mainly use macOS at work but NixOS for anything personal, as well as servers. I can maintain roughly consistent, through code, environments with only minor tweaks per machine. This means I have essentially the same development environment at work and at home for anything in the terminal. Another big benefit is, if anything breaks, you can always roll back with Nix. Or, since it's code, it's very easy to start with a clean slate. I recently changed Macbooks and, with only a minor tweak to account for the ARM chip instead of Intel, I was up-and-running with my entire environment exactly as it was, with the only time accounted for being package download and installation, essentially. -- The main problem that Brew solves that Nix does not (well, it does, but it defers to Brew to do so), is installation of graphical applications. There is an open Apple bug on this issue IIRC - I don't recall all the specific details at this moment, however.