I echo the above. I used to work at an airport where arriving passengers were required to complete a form.
In the box marked "Nationality" they were required to write the nation from which they held a passport (British, American/USA, Mexico, Malaysia etc). Mainly with American passengers, we frequently found such things as "Caucasian" or "African American" in that box, which in BrE would be "race" or "ethnic origin".
American travellers said that had the box been marked "Citizenship" they would have written "American".
So there is a difference in meaning depending on where you are. In BrE, nationality certainly has nothing to do with race or ethnic origin, it's entirely what passport you hold (or would hold if you had one).