They're differentiated by not calling a viewfinder camera an RF, because they're not. An RF has a rangefinder mechanism; a viewfinder camera doesn't!

I should clarify that parallax is something else entirely from an RF patch. Parallax refers to the inaccuracy of the viewfinder at close distances, in just the same way that the views of your two eyes differ. So a camera with parallax correction actually moves the framelines around a little as you change the focus, or have a slightly indented second frameline. This is not to be confused with an RF patch.