Yum! Brands owns both, and Pizza Hut, Taco Bell, KFC, etc. The restaurants themselves are owned by franchisees who license the trademarks (and all kind of complicated buy-in and standards).
Yum! Brands made ThighStop to address the wing shortage and keep the association/credibility. It’s actually weirdly transparent: just like WingStop, but thighs. I don’t know if WingStop franchisees got automatic rights to that brand or not. My guess is that it was just a way to keep them afloat.
Now, the fact that WingStop has any cred is gross. I can get better wings from a mom & pop or local chain at any strip mall, or heck, a gas station than wing chains like them, BWW, etc.
I guess America outside the South and Buffalo, NY doesn’t have access to wings that don’t taste like a salt lick. It’s a tragedy.