Sunday punch vs haymaker

Sunday punch and haymaker both are nouns.

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

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

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

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

Sunday 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