This is a US-vs-everyone-else terminology difference. In most of the world "state" refers to a sovereign entity, "nation" refers to an ethnic group, and "nation

This is a US-vs-everyone-else terminology difference. In most of the world "state" refers to a sovereign entity, "nation" refers to an ethnic group, and "nation-state" is a state identified with an ethnic nation. But all of that terminology solidified in the 19th century, so outside of academic political science the US uses "state" to refer to individual entities in a federation (e.g. translating German "Bundesland" as "state"), "nation" to refer to not-necessarily-ethnic bodies politick, and "nation-state" to specify "what we call a nation, what the Old World calls a state". Which of course leads to a lot of confusion about the connotations of "EU member state", which in European discourse implies real sovereignty, but in US discourse implies a federalist Europe.