The answer is it depends. Claude's generally better at frontend and debugging tasks, while Codex is stronger at backend features and exploratory work. They have very different coding styles and thus very different strengths.

Any actual data backing this up? Or is this just your personal experience?

Just personal experience, I just find it way easier to do frontend work with Claude than it is with Codex.

No, this is all nonsense.

It is so hard to tell at this point between the models to make generalizations like this.

Just complete nonsense.