Chemistry is the same for each of us, as is physics, so I'd be inclined to think that red is the same red for everyone.

You'd be inclined to, but no, of the little we do understand about human perception, we do understand enough by now to say that different people can genuinely experience and perceive the world differently, sometimes wildly so.

Look into aphantasia (lack of mental imagery), anendophasia (lack of inner voice).