caviare vs hard roe

caviare and hard roe both are nouns.

Word	Noun	Adjective	Verb	Adverb
caviare	Yes	No	No	No
hard roe	Yes	No	No	No

As nouns, hard roe is a hypernym of caviare; that is, hard roe is a word with a broader meaning than caviare:

caviare: salted roe of sturgeon or other large fish; usually served as an hors d'oeuvre
hard roe: fish eggs or egg-filled ovary; having a grainy texture

Other hypernyms of caviare include roe.

caviare (noun)	hard roe (noun)
salted roe of sturgeon or other large fish; usually served as an hors d'oeuvre	fish eggs or egg-filled ovary; having a grainy texture