breakup vs rupture

breakup and rupture both are nouns.

Word	Noun	Adjective	Verb	Adverb
breakup	Yes	No	No	No
rupture	Yes	No	Yes	No

As nouns, rupture is a hyponym of breakup; that is, rupture is a word with a more specific, narrower meaning than breakup:

Other hyponyms of breakup include breach, break, falling out, rift, severance, break.

breakup (noun)	rupture (noun)
the termination or disintegration of a relationship (between persons or nations)	the act of making a sudden noisy break
coming apart	a personal or social separation (as between opposing factions)
	state of being torn or burst open

breakup (verb)	rupture (verb)
	separate or cause to separate abruptly