water dog vs sporting dog

water dog and sporting dog both are nouns.

Word	Noun	Adjective	Verb	Adverb
water dog	Yes	No	No	No
sporting dog	Yes	No	No	No

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

water dog: a dog accustomed to water and usually trained to retrieve waterfowl
sporting dog: a dog trained to work with sportsmen when they hunt with guns

Other hypernyms of water dog include gun dog.

water dog (noun)	sporting dog (noun)
a dog accustomed to water and usually trained to retrieve waterfowl	a dog trained to work with sportsmen when they hunt with guns
a person who enjoys being in or on the water