American coot vs water hen

American coot and water hen both are nouns.

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

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

Other synonyms of American coot include Fulica americana, marsh hen, mud hen.

American coot (noun)	water hen (noun)
a coot found in North America	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