tortoiseshell vs tortoiseshell butterfly

tortoiseshell and tortoiseshell butterfly both are nouns.

Word	Noun	Adjective	Verb	Adverb
tortoiseshell	Yes	No	No	No
tortoiseshell butterfly	Yes	No	No	No

As nouns, tortoiseshell and tortoiseshell butterfly are synonyms defined as:

tortoiseshell and tortoiseshell butterfly: brilliantly colored; larvae feed on nettles

tortoiseshell (noun)	tortoiseshell butterfly (noun)
a cat having black and cream-colored and yellowish markings	brilliantly colored; larvae feed on nettles
brilliantly colored; larvae feed on nettles
the mottled horny substance of the shell of some turtles