annexation vs acquisition

annexation and acquisition both are nouns.

Word	Noun	Adjective	Verb	Adverb
annexation	Yes	No	No	No
acquisition	Yes	No	No	No

As nouns, acquisition is a hypernym of annexation; that is, acquisition is a word with a broader meaning than annexation:

annexation: the formal act of acquiring something (especially territory) by conquest or occupation
acquisition: the act of contracting or assuming or acquiring possession of something

annexation (noun)	acquisition (noun)
the formal act of acquiring something (especially territory) by conquest or occupation	the act of contracting or assuming or acquiring possession of something
incorporation by joining or uniting	an ability that has been acquired by training
	the cognitive process of acquiring skill or knowledge
	something acquired