In Data, an event can be assigned to a category, the category is then usable in filters, is surfaced in Segmentations, Funnels, etc. It’s very useful for data governance and easy finding of events by end users.
the same can’t be said of “tags”…they don’t really do much. If you were to make these more useful in a way akin to categories, it’d add a further layer of beneficial governance and usability!