solar day vs 24-hour interval

solar day and 24-hour interval both are nouns.

Word	Noun	Adjective	Verb	Adverb
solar day	Yes	No	No	No
24-hour interval	Yes	No	No	No

As nouns, solar day and 24-hour interval are synonyms defined as:

solar day and 24-hour interval: time for Earth to make a complete rotation on its axis

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

solar day (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