User blog comment:VuLinhAssassin/Testing - Ootsubo Yuka (Demo Seiyuu page)/@comment-26154973-20180102152436/@comment-26154973-20180102180747

Those data and collection (Lua) modules are used as a (non-relational) database. You can see -- return { ... } (e.g., Module:Ayanami) as a "document", while collections are there for "queries" (e.g., Module:Collection/Equipment, allowing Module:Iterator, List of Main Guns by stats, etc.).