État de droit is more centralized on the concept of delimitation of the State and it's legitimacy, in a context of civil law, while rule of law is related to the "supremacy of law" in a broader sense, even tho the first is enforced by the latter

But there are many distinct concepts (i think the most prominent in german law and therefore brazilian law, being from Hans Kelsen), and there are many international organizations that uses both concepts interchargeably