tortoiseshell vs domestic cat

tortoiseshell and domestic cat both are nouns.

Word	Noun	Adjective	Verb	Adverb
tortoiseshell	Yes	No	No	No
domestic cat	Yes	No	No	No

As nouns, domestic cat is a hypernym of tortoiseshell; that is, domestic cat is a word with a broader meaning than tortoiseshell:

Other hypernyms of tortoiseshell include Felis catus, Felis domesticus, house cat.

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