nighttime vs twenty-four hours

nighttime and twenty-four hours both are nouns.

Word	Noun	Adjective	Verb	Adverb
nighttime	Yes	No	No	No
twenty-four hours	Yes	No	No	No

nighttime (noun)	twenty-four hours (noun)
the time after sunset and before sunrise while it is dark outside	time for Earth to make a complete rotation on its axis