We were purchasing some tumblers with our company logo for giveaways at work a couple years ago. Along with their samples, the company that applies the logos actually brought along Yeti, Rtic and Ozark Mountain (WalMart brand) tumblers that were sliced in half to compare the construction. According to them, the Yeti and Ozark Mountain were identical and their accessories were interchangeable. We were told that the Rtic is basically a copy of the Yeti with some slight variations. (IIRC the Yeti and Ozark Mountain were 32 oz. tumblers and the Rtic was 30 oz.) Needless to say, we bought the cheapest ones for the giveaway.
If you check out the online tests of these tumblers, they test almost identically.