pen vs quill

pen and quill both are nouns.

Word	Noun	Adjective	Verb	Adverb
pen	Yes	No	Yes	No
quill	Yes	No	No	No

As nouns, quill is a hyponym of pen; that is, quill is a word with a more specific, narrower meaning than pen:

pen (noun)	quill (noun)
female swan	a stiff hollow protective spine on a porcupine or hedgehog
a writing implement with a point from which ink flows	the hollow spine of a feather
an enclosure for confining livestock	any of the larger wing or tail feathers of a bird
a correctional institution for those convicted of major crimes	pen made from a bird's feather
a portable enclosure in which babies may be left to play

pen (verb)	quill (verb)
produce a literary work