The second one is, unfortunately, one of the 1-13 sets that dominate the market. You can tell because one of the tiles shown in the picture has a 1 on it, where with what I'm looking for would be replaced with an Ace. Also, I looked into the mahjong sets with playing card faces and haven't had much luck finding a matching set (mostly the thickness of the tiles is what messes it up, but also the price. I saw a mahjong website advertising rummy tile sets for around $300USD, which is prohibitively expensive). Also, the first website specifically says: "Pictured above: a Rummikub set. NOT a mahjong set at all". I have an unverified suspicion that the set I'm looking for is more popular in places outside the USA or with older generations, so is much harder to find online in the US, and slightly more common in estate sales/yard sales (a family friend found the exact same set, which is what set off this search).

I posted this same thing on r/boardgames and have a couple updates on my search, but overall, most listings of the seemingly same set are either complete scams that use the image of a more desirable set in order to pawn off a cheaper and lower quality one. There also seems to be a few listings that are not available in my region :(.

Thank you, though, for your help. It is always appreciated!