grass wrack vs Zostera marina

grass wrack and Zostera marina both are nouns.

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

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

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

Other synonyms of grass wrack include eelgrass, sea wrack.

grass wrack (noun)	Zostera marina (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