NB vs notation

NB and notation both are nouns.

Word	Noun	Adjective	Verb	Adverb
NB	Yes	No	No	No
notation	Yes	No	No	No

As nouns, notation is a hypernym of NB; that is, notation is a word with a broader meaning than NB:

NB: a Latin phrase (or its abbreviation) used to indicate that special attention should be paid to something
notation: a comment or instruction (usually added)

Other hypernyms of NB include annotation, note.

NB (noun)	notation (noun)
a Latin phrase (or its abbreviation) used to indicate that special attention should be paid to something	the activity of representing something by a special system of marks or characters
	a technical system of symbols used to represent special things
	a comment or instruction (usually added)