Anecdotally, working on an old Vue 2 app I found Claude would almost always return "refactors" as React + Tailwind the first time, and need nudging back into using Vue 2.
I've tried both and am currently using MathAcademy to learn new knowledge. It's very, very good at incrementally building out concepts and gradually adding complexity. I had no luck at all with Brilliant. MathAcademy practically forces you to bust out a pencil and paper and dive into problems, but Brilliant was more like watching a kind of neat YouTube video on a topic.
Fantastic resource! I actually stumbled across it organically a few months ago, and couldn't believe my luck. There's really nothing else out there as high quality that's CC0. So thank you.