place kick vs kickoff

place kick and kickoff both are nouns.

Word	Noun	Adjective	Verb	Adverb
place kick	Yes	No	No	No
kickoff	Yes	No	No	No

As nouns, kickoff is a hyponym of place kick; that is, kickoff is a word with a more specific, narrower meaning than place kick:

place kick: (sports) a kick in which the ball is placed on the ground before kicking
kickoff: (football) a kick from the center of the field to start a football game or to resume it after a score

Other hyponyms of place kick include free kick.

place kick (noun)	kickoff (noun)
(sports) a kick in which the ball is placed on the ground before kicking	(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