I don't think this distinction is unclear.
In and of itself, a racial nationalist's beliefs might be something close to "I prefer to live in a country with my own people."
In and of itself, a racial supremacist's beliefs might be something close to "My people are inherently superior and should rule over others."
Anyway, I'm mainly just interested in this person's starting point and the effect that his trip had on him, as well as calling out the media for not being precise about these issues. Nationalist and Supremacist are not synonyms: that's lazy click-baiting journalism.