twenty-four hours vs 24-hour interval

twenty-four hours and 24-hour interval both are nouns.

Word	Noun	Adjective	Verb	Adverb
twenty-four hours	Yes	No	No	No
24-hour interval	Yes	No	No	No

As nouns, twenty-four hours and 24-hour interval are synonyms defined as:

twenty-four hours and 24-hour interval: time for Earth to make a complete rotation on its axis

Other synonyms of twenty-four hours include day, mean solar day, solar day, twenty-four hour period.

twenty-four hours (noun)	24-hour interval (noun)
time for Earth to make a complete rotation on its axis	time for Earth to make a complete rotation on its axis