flight feather vs plumage

flight feather and plumage both are nouns.

Word	Noun	Adjective	Verb	Adverb
flight feather	Yes	No	No	No
plumage	Yes	No	No	No

As nouns, plumage is a hypernym of flight feather; that is, plumage is a word with a broader meaning than flight feather:

flight feather: any of the larger wing or tail feathers of a bird
plumage: the light horny waterproof structure forming the external covering of birds

Other hypernyms of flight feather include plume.

flight feather (noun)	plumage (noun)
any of the larger wing or tail feathers of a bird	the light horny waterproof structure forming the external covering of birds