Someone described Poshmark as competitor to StitchFix or Rent the Runway, and that completely missed the mark on all the products.

Comparing StitchFix to Rent the Runway doesn't seem right either, as StitchFix doesn't loan you the clothes, you buy them. I have purchased three fixes from them so far. From what we can tell, its their own brands they sell.

Agreed, Poshmark doesn't have a clear statement of what it actually is on the landing page. My wife sells her old clothes on there, so I liken it to eBay as some have mentioned.

TL;DR - Poshmark: eBay/Craigslist/OfferUp/LetGo for used clothes - StitchFix: curated clothes (hand picked), subscription based - Rent the Runway: rent clothes, allows for clothes to not collect dust in a closet