Distributions are preconfigured and tested versions of AROS. They contain a lot of useful user applications that don't come with the main AROS.org binaries and will be of great interest to users. They may not have the latest core system, but their stability and user-friendliness is much greater than those of the nightly builds. If you are a user interested in checking what AROS has to offer, use the distributions to get the most complete AROS experience.