hard roe vs roe

hard roe and roe both are nouns.

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

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

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

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