Localization is adapting software so that it works well in a given locale. This is typically understood to be the translation of a user interface. This is however not everything that should be understood in this way. There are also things like sort orders, date formats and many other things that should be considered.
We are really fortunate in that the MediaWiki software has had internationalization in mind. Internationalization is creating an architecture that makes localization possible, and providing defined way of doing it. Because of all the efforts of the past and the continued effort in maintaining the user interface, MediaWiki is a platform that can host OmegaWiki.