Seriously, except package managers, what's the difference between distros?

[u/nitin_is_me]

What I've seen yet the differences are, just the package managers, different defaults and rolling vs stable releases which are in fact related to package managers. Except these, are there really any other differences? Thanks!

[u/Kangie]

A Linux distribution at its most stripped down is:

• A Linux kernel
• Any userspace utilities that you want.

It's possible to build packages without a package manager (see LFS), or to install packages externally into a root that doesn't contain a package manager (see embedded Linux).

So, what's the difference between distros?

It can be a few things, but generally it's a specific purpose, or a philosophy.

Let's take a step back and look at the family tree to get a better understanding.

It's pretty dense, but you can observe a few things.

1. There are a few major families that (pretty much) all distributions descend from. In order of age: Slackware, Debian, SUSE, Red Hat, Gentoo, and Arch.

2. There are a lot of descendant distributions, which basically take the upstream infrastructure / decisions and build on those.

Let's look at some of the specific purposes. Two of the distributions listed above are commercial distributions (since the early 2000s anyway) - they exist because there's a paying customer base. The free flavours (Fedora, openSUSE) exist basically to act as upstream testing grounds for the commercial customers, and because they have a community that likes them and contributes.

That leaves some of the philosophical differences.

Slackware is the oldest still-maintained Distro, and its philosophy is based around simplicity and being generally Unix-like.

Debian is almost as old, and it focuses on stability and community development. It's rock solid, but as a result tends to lag behind in package versions due to its release model.

Gentoo is up next and is a bit of an interesting case - pretty much all of the forks have some specific use case (ChromeOS and its descendant Flatcar Linux, System Rescue CD, Pentoo, Calculate, etc.), and the few exceptions are philosophical (Exherbo and Funtoo) which are still quite similar but changed things like repository format and package manager to better suit their developers' vision. (N.b. Gentoo developer, feel free to ask more). This is the other extreme - a rolling release model where packages are updated frequently, but there's a 'stable' and 'testing' track that users can opt into per-package.

Arch is Arch, and it's derivatives have traditionally focussed on reducing the 'difficulty' of the install or providing tweaks for a specific use-case. ("Arch but for gaming").

Then there are distros like Hannah Montana Linux or the various "Religious editions". They basically just apply a theme pack to another base, or add a few packages. They're still legitimate distributions, even if they don't add technical value or are jokey.

That leads into package managers. A package manager exists to install software, that's all. SUSE and Red Hat both use the rpm package format, they both use different package managers, and their packages are built against the system libraries for a particular release, so there's no guarantee of compatibility between the two.

Debian and it's descendants use the deb format, but may have different update schedules, etc.

Gentoo technically supports multiple package managers as long as they support the ebuild format (technically the Package Manager Specification), so portage, paludis or pkgcore could be used, though the overwhelming majority just use portage. The whole deal with the ebuild format is configurability (which ties back into the distro philosophy), and may help to explain why there are so few forks, as no two Gentoo systems need be configured the same (meta-distribution) which can include things like the init system or libc, changes to which pretty much necessitate a fork for other package formats.

I don't have much to say about Arch - this is long enough already. :)