There are new ideas in all of his books, it's just that specific ones have sections from previous ones because some are compilations. I haven't read Economics and Politics of Race, I suspect that's a much earlier one.

I'd say that Intellectuals and Race goes over the nature of intellectuals, why they pursue racial polices (which effectively allows some groups of intellectuals to supersede other intellectuals), and the history of them doing so. There's plenty of stuff on the American transition of progressive racialism to progressive intellectual anti-racism, along with the European rivalries between German, Chek, and Jewish intellectuals that lead to the international support of Nazism among the intellectual elite.