24-hour interval vs twenty-four hour period

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

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

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

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

Other synonyms of 24-hour interval include day, mean solar day, solar day, twenty-four hours.

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