[LM_NucleusCMS] (http://nucleus.slightlysome.net/) is a fork of [NucleusCMS] (http://www.nucleuscms.org/). The reason for this fork is that currently is the Nucleus CMS project abandoned by its developers and the latest version of Nucleus CMS has serious bugs that makes it unusable on newer versions of PHP.
[LM_NucleusCMS] (http://nucleus.slightlysome.net/) is 100% compatible with [NucleusCMS] (http://www.nucleuscms.org/) and fixes all known bugs in version 3.65 of Nucleus CMS.
LM_NucleusCMS::MOON takes things one step further seeking a pure OO approach to NucleusCMS.
MOON is 100% compatible with LM_NucleusCMS for the time being as it currently sits as a wrapper on top of it.