quill pen vs pen

quill pen and pen both are nouns.

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

As nouns, pen is a hypernym of quill pen; that is, pen is a word with a broader meaning than quill pen:

quill pen (noun)	pen (noun)
pen made from a bird's feather	female swan
	a writing implement with a point from which ink flows
	an enclosure for confining livestock
	a correctional institution for those convicted of major crimes
	a portable enclosure in which babies may be left to play

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