eelgrass vs grass wrack

eelgrass and grass wrack both are nouns.

Word	Noun	Adjective	Verb	Adverb
eelgrass	Yes	No	No	No
grass wrack	Yes	No	No	No

As nouns, eelgrass and grass wrack are synonyms defined as:

eelgrass and grass wrack: submerged marine plant with very long narrow leaves found in abundance along North Atlantic coasts

Other synonyms of eelgrass include sea wrack, Zostera marina.

eelgrass (noun)	grass wrack (noun)
submerged marine plant with very long narrow leaves found in abundance along North Atlantic coasts	submerged marine plant with very long narrow leaves found in abundance along North Atlantic coasts
submerged aquatic plant with ribbonlike leaves; Old World and Australia