Zostera marina vs grass wrack

Zostera marina and grass wrack both are nouns.

Word	Noun	Adjective	Verb	Adverb
Zostera marina	Yes	No	No	No
grass wrack	Yes	No	No	No

As nouns, Zostera marina and grass wrack are synonyms defined as:

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

Other synonyms of Zostera marina include eelgrass, sea wrack.

Zostera marina (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