Should I register a distribution or an upstream project?

Launchpad allows you to register your free software project as two separate types: upstream projects and distributions.

In general, upstream projects represent projects that work on one specific software package; this normally implies they periodically release their software as tarballs, and offer public access to their revision control system.

Distributions in Launchpad are meant to represent Linux distributions: projects which integrate a number of different software packages and compose them into an operating system. They normally use a packaging system (such as RPM or deb or freebsd and gentoo's build systems) and do relatively small changes to the software packages they compose.

In Launchpad, upstream projects are self-registered; anyone with an account can visit https://launchpad.net/projects/+new-guided and create a new project. They are subject to screening to ensure that they actually represent free software projects. Distributions are registered only by Launchpad admins.

There are currently two Launchpad limitations that might cause you to want to register your Linux distribution as a regular "upstream" project. First, currently only upstream projects have access to the Code and Translations applications in Launchpad. Second, distributions are unable to register product releases and therefore don't have access to release and milestone targeting.