coonhound vs hound dog

coonhound and hound dog both are nouns.

Word	Noun	Adjective	Verb	Adverb
coonhound	Yes	No	No	No
hound dog	Yes	No	No	No

As nouns, hound dog is a hypernym of coonhound; that is, hound dog is a word with a broader meaning than coonhound:

coonhound: any of several breeds of hound developed for hunting raccoons
hound dog: any of several breeds of dog used for hunting typically having large drooping ears

Other hypernyms of coonhound include hound.

coonhound (noun)	hound dog (noun)
any of several breeds of hound developed for hunting raccoons	any of several breeds of dog used for hunting typically having large drooping ears