marsh hen vs American coot

marsh hen and American coot both are nouns.

Word	Noun	Adjective	Verb	Adverb
marsh hen	Yes	No	No	No
American coot	Yes	No	No	No

As nouns, marsh hen and American coot are synonyms defined as:

Other synonyms of marsh hen include Fulica americana, mud hen, water hen.

marsh hen (noun)	American coot (noun)
any of various small aquatic birds of the genus Gallinula distinguished from rails by a frontal shield and a resemblance to domestic hens	a coot found in North America
a coot found in North America