24-hour interval vs mean solar day

24-hour interval and mean solar day both are nouns.

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

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

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

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

24-hour interval (noun)	mean solar day (noun)
time for Earth to make a complete rotation on its axis	time for Earth to make a complete rotation on its axis