annotate vs pen

annotate is not a noun while pen is a noun.

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

As verbs, pen is a hypernym of annotate; that is, pen is a word with a broader meaning than annotate:

Other hypernyms of annotate include compose, indite, write.

annotate (noun)	pen (noun)
	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

annotate (verb)	pen (verb)
provide interlinear explanations for words or phrases	produce a literary work
add explanatory notes to or supply with critical comments