alley cat vs domestic cat

alley cat and domestic cat both are nouns.

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

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

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

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