cinch vs duck soup

cinch and duck soup both are nouns.

Word	Noun	Adjective	Verb	Adverb
cinch	Yes	No	Yes	No
duck soup	Yes	No	No	No

As nouns, cinch and duck soup are synonyms defined as:

Other synonyms of cinch include breeze, child's play, picnic, piece of cake, pushover, snap, walkover.

cinch (noun)	duck soup (noun)
a form of all fours in which the players bid for the privilege of naming trumps	any undertaking that is easy to do
any undertaking that is easy to do
stable gear consisting of a band around a horse's belly that holds the saddle in place