Nix vs Portage

Nix is a purely functional package management system. This means that the act of building a package does not have side effects, such as destructively updating or deleting files that may be used by other packages.

Nix allows the creation of project-specific shell and build environments which are isolated from the rest of the system. These environments are defined declaratively to ensure reproducibility.

Because of the functional approach it takes, Nix makes it easy for systems to use multiple versions of the same package simultaneously, and ensure that updating or removing a package can't break other packages.

No more of the traditional: "it works on my machine". When it says reproducible, this is the real deal.

WIth portage you can decide and customize which dependencies to install through some thing called USE flags. These are keywords that when defined, will tell Portage that you want support for the chosen keyword.

Portage uses a sandbox as a safety measure during build processes. This is done to ensure that no packages accidentally write outside a 'safe' location.

Slotting is a feature which allows users to install multiple versions of a software simultaneously. This is especially useful for libraries which have changed interfaces between versions.

With portage you can either compile packages from source or you can download and install their binary versions.

If you need faster resolution, you can run pkgcore for search and portage for installing, and they work well together.

Adding supplemental repositories, aka overlays, is easy with eselect-repository or layman.

By default, portage doesn't delete or move any customized config files, thus enabling competent users to modify any config file however they want.

With portage you can view a list of all the programs that you can install by going to /usr/portage and running ls.

You can fully control all packages if you use it properly.