marsh hen vs water hen

marsh hen and water hen both are nouns.

Word	Noun	Adjective	Verb	Adverb
marsh hen	Yes	No	No	No
water hen	Yes	No	No	No

As nouns, marsh hen and water hen are synonyms defined as:

marsh hen and water hen: any of various small aquatic birds of the genus Gallinula distinguished from rails by a frontal shield and a resemblance to domestic hens

Other synonyms of marsh hen include gallinule, swamphen.

As nouns, marsh hen and water hen are synonyms defined as:

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

marsh hen (noun)	water hen (noun)
any of various small aquatic birds of the genus Gallinula distinguished from rails by a frontal shield and a resemblance to domestic hens	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