Belgian sheepdog vs sheep dog

Belgian sheepdog and sheep dog both are nouns.

Word	Noun	Adjective	Verb	Adverb
Belgian sheepdog	Yes	No	No	No
sheep dog	Yes	No	No	No

As nouns, sheep dog is a hypernym of Belgian sheepdog; that is, sheep dog is a word with a broader meaning than Belgian sheepdog:

Belgian sheepdog: hardy working dog developed in Belgium for herding sheep
sheep dog: any of various usually long-haired breeds of dog reared to herd and guard sheep

Other hypernyms of Belgian sheepdog include sheepdog, shepherd dog.

Belgian sheepdog (noun)	sheep dog (noun)
hardy working dog developed in Belgium for herding sheep	any of various usually long-haired breeds of dog reared to herd and guard sheep