Do we really need journalists and readers spending effort dwelling on the intellectual distinctions between white supremacism and white nationalism? Is that a topic of discussion our society needs to focus on? What practical difference does it make in describing existing political movements?

If there were some white nationalist group that espoused moving to predominantly white countries (or really starting their own country [0]), while being completely tolerant of the domestic state of affairs and distancing themselves from those who seek to turn this has-always-been-diverse country into their desired ethnostate, then perhaps the distinction would be relevant. But lacking that, it's a distinction without a difference.

[0] I don't know that there are any countries that are predominantly "white" but not better defined by a more specific term. It would seem that "white" nationalism is itself the product of "miscegenation" between various traditional nationalities. Nobody really balks at "$traditionally_white_nationality pride", or even larger pan- terms like European or Slavic pride. It's the attempt to take credit for nothing more than a lighter skin tone that is the problem.