domestic cat vs house cat

domestic cat and house cat both are nouns.

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

As nouns, domestic cat and house cat are synonyms defined as:

Other synonyms of domestic cat include Felis catus, Felis domesticus.

domestic cat (noun)	house cat (noun)
any domesticated member of the genus Felis	any domesticated member of the genus Felis