roe vs caviare

roe and caviare both are nouns.

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

As nouns, caviare is a hyponym of roe; that is, caviare is a word with a more specific, narrower meaning than roe:

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

Other hyponyms of roe include coral, caviar, shad roe.

roe (noun)	caviare (noun)
eggs of female fish	salted roe of sturgeon or other large fish; usually served as an hors d'oeuvre
the eggs or egg-laden ovary of a fish
the egg mass or spawn of certain crustaceans such as the lobster
fish eggs or egg-filled ovary; having a grainy texture