These are packages that the Xubuntu team considers important, and should take precedence when translating.
These packages only exist in Xubuntu, so their translation is solely dealt with by Xubuntu translators. These are of high importance for the Xubuntu team.
These packages are used by Xubuntu and provide features to the Xubuntu experience. When these are translated, the base system is immediately more usable for more people.