The nine categories show where or how their outfits are obtained, while the four types simply indicate how the item is worn: as an outfit, adornment, head adornment, or face adornment. The Wardrobe is split into nine different categories and four types.
This feature serves the purpose of managing most available cosmetic or faction outfits throughout the game without having to store them in the player vault or inventory. Non-premium players can still see and preview outfits in the wardrobe and withdraw previously placed outfits, but won't be able to place them there again without an active premium account.
It is accessible via the in-game menu or by pressing the F3 key. The Wardrobe is a storage-based system that is exclusive to players who have purchased a Premium membership with NCoins.