alley cat vs house cat

alley cat and house cat both are nouns.

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

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

Other hypernyms of alley cat include domestic cat, Felis catus, Felis domesticus.

alley cat (noun)	house cat (noun)
a homeless cat	any domesticated member of the genus Felis