reunion vs unification

reunion and unification both are nouns.

Word	Noun	Adjective	Verb	Adverb
reunion	Yes	No	No	No
unification	Yes	No	No	No

As nouns, unification is a hypernym of reunion; that is, unification is a word with a broader meaning than reunion:

Other hypernyms of reunion include conjugation, jointure, union, uniting.

reunion (noun)	unification (noun)
the act of coming together again	the act of making or becoming a single unit
a party of former associates who have come together again	an occurrence that involves the production of a union
	the state of being joined or united or linked