knockout punch vs Sunday punch

knockout punch and Sunday punch both are nouns.

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

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

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

Other synonyms of knockout punch include haymaker, KO punch.

knockout punch (noun)	Sunday punch (noun)
a hard punch that renders the opponent unable to continue boxing	a hard punch that renders the opponent unable to continue boxing