annotation vs expansion

annotation and expansion both are nouns.

Word	Noun	Adjective	Verb	Adverb
annotation	Yes	No	No	No
expansion	Yes	No	No	No

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

Other hypernyms of annotation include expanding upon.

annotation (noun)	expansion (noun)
the act of adding notes	the act of increasing (something) in size or volume or quantity or scope
a comment or instruction (usually added)	adding information or detail
	a discussion that provides additional information
	a function expressed as a sum or product of terms