knockout punch vs haymaker

knockout punch and haymaker both are nouns.

Word	Noun	Adjective	Verb	Adverb
knockout punch	Yes	No	No	No
haymaker	Yes	No	No	No

As nouns, knockout punch and haymaker are synonyms defined as:

knockout punch and haymaker: a hard punch that renders the opponent unable to continue boxing

Other synonyms of knockout punch include KO punch, Sunday punch.

knockout punch (noun)	haymaker (noun)
a hard punch that renders the opponent unable to continue boxing	a hard punch that renders the opponent unable to continue boxing
	a farm machine that treats hay to cause more rapid and even drying