showtime vs kickoff

showtime and kickoff both are nouns.

Word	Noun	Adjective	Verb	Adverb
showtime	Yes	No	No	No
kickoff	Yes	No	No	No

As nouns, showtime and kickoff are synonyms defined as:

Other synonyms of showtime include beginning, commencement, first, get-go, offset, outset, start, starting time.

showtime (noun)	kickoff (noun)
the time at which something is supposed to begin	(football) a kick from the center of the field to start a football game or to resume it after a score
	a start given to contestants
	the time at which something is supposed to begin