domestic dog vs bow-wow

domestic dog and bow-wow both are nouns.

Word	Noun	Adjective	Verb	Adverb
domestic dog	Yes	No	No	No
bow-wow	Yes	No	No	No

As nouns, bow-wow is a hyponym of domestic dog; that is, bow-wow is a word with a more specific, narrower meaning than domestic dog:

domestic dog: a member of the genus Canis (probably descended from the common wolf) that has been domesticated by man since prehistoric times; occurs in many breeds
bow-wow: informal terms for dogs

domestic dog (noun)	bow-wow (noun)
a member of the genus Canis (probably descended from the common wolf) that has been domesticated by man since prehistoric times; occurs in many breeds	informal terms for dogs
	the bark of a dog