bloodhound vs hound dog

bloodhound and hound dog both are nouns.

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

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

bloodhound: a breed of large powerful hound of European origin having very acute smell and used in tracking
hound dog: any of several breeds of dog used for hunting typically having large drooping ears

Other hypernyms of bloodhound include hound.

bloodhound (noun)	hound dog (noun)
a breed of large powerful hound of European origin having very acute smell and used in tracking	any of several breeds of dog used for hunting typically having large drooping ears