pen vs quill pen

pen and quill pen both are nouns.

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

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

pen (noun)	quill pen (noun)
female swan	pen made from a bird's feather
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

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