primary feather vs primary quill

primary feather and primary quill both are nouns.

Word	Noun	Adjective	Verb	Adverb
primary feather	Yes	No	No	No
primary quill	Yes	No	No	No

As nouns, primary feather and primary quill are synonyms defined as:

primary feather and primary quill: one of the main flight feathers projecting along the outer edge of a bird's wing

Other synonyms of primary feather include primary.

primary feather (noun)	primary quill (noun)
one of the main flight feathers projecting along the outer edge of a bird's wing	one of the main flight feathers projecting along the outer edge of a bird's wing