Fable and Narrative are different. In the translation of the novel I read, they helped to represent different levels of constellations for example. Fable-grade represented the more powerful constellations like the leaders of a nebula, and if I remember correctly Narrative-grade was the level of stronger, but not that much stronger types of constellations. The whole leveling system of the constellations got super confusing for a bit cause there’s upper and lower-grades. So I’d say, keep your vocabulary very open. It’ll get confusing if you only use one word for everything.