N.B. vs annotation

N.B. and annotation both are nouns.

Word	Noun	Adjective	Verb	Adverb
N.B.	Yes	No	No	No
annotation	Yes	No	No	No

As nouns, annotation is a hypernym of N.B.; that is, annotation is a word with a broader meaning than N.B.:

N.B.: a Latin phrase (or its abbreviation) used to indicate that special attention should be paid to something
annotation: a comment or instruction (usually added)

Other hypernyms of N.B. include notation, note.

N.B. (noun)	annotation (noun)
a Latin phrase (or its abbreviation) used to indicate that special attention should be paid to something	the act of adding notes
	a comment or instruction (usually added)