WDAS and Pixar are two separate studios owned by Disney the company. There are other studios under the Disney umbrella such as ILM, Live Action, Blue Sky (closed), Disneytoon (closed), DTA (TV Animation)

Aren’t they still separate studios, but same owner?

Wasn’t that part of the take over conditions? I seem to recall this from the Steve Jobs bio.

Regardless, the brand “Pixar” gives you different expectations to the story than “Disney “