zucchini vs marrow squash

zucchini and marrow squash both are nouns.

Word	Noun	Adjective	Verb	Adverb
zucchini	Yes	No	No	No
marrow squash	Yes	No	No	No

As nouns, marrow squash is a hypernym of zucchini; that is, marrow squash is a word with a broader meaning than zucchini:

zucchini: marrow squash plant whose fruit are eaten when small
marrow squash: any of various squash plants grown for their elongated fruit with smooth dark green skin and whitish flesh

Other hypernyms of zucchini include marrow, vegetable marrow.

zucchini (noun)	marrow squash (noun)
small cucumber-shaped vegetable marrow; typically dark green	any of various squash plants grown for their elongated fruit with smooth dark green skin and whitish flesh
marrow squash plant whose fruit are eaten when small