roe vs hard roe

roe and hard roe both are nouns.

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

As nouns, roe and hard roe are synonyms defined as:

roe and hard roe: fish eggs or egg-filled ovary; having a grainy texture

roe (noun)	hard roe (noun)
eggs of female fish	fish eggs or egg-filled ovary; having a grainy texture
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