big bang vs blowup

big bang and blowup both are nouns.

Word	Noun	Adjective	Verb	Adverb
big bang	Yes	No	No	No
blowup	Yes	No	No	No

As nouns, blowup is a hypernym of big bang; that is, blowup is a word with a broader meaning than big bang:

big bang: (cosmology) the cosmic explosion that is hypothesized to have marked the origin of the universe
blowup: a violent release of energy caused by a chemical or nuclear reaction

Other hypernyms of big bang include detonation, explosion.

big bang (noun)	blowup (noun)
(cosmology) the cosmic explosion that is hypothesized to have marked the origin of the universe	a photographic print that has been enlarged
	an unrestrained expression of emotion
	a violent release of energy caused by a chemical or nuclear reaction