German police dog vs sheep dog

German police dog and sheep dog both are nouns.

Word	Noun	Adjective	Verb	Adverb
German police dog	Yes	No	No	No
sheep dog	Yes	No	No	No

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

German police dog: breed of large shepherd dogs used in police work and as a guide for the blind
sheep dog: any of various usually long-haired breeds of dog reared to herd and guard sheep

Other hypernyms of German police dog include sheepdog, shepherd dog.

German police dog (noun)	sheep dog (noun)
breed of large shepherd dogs used in police work and as a guide for the blind	any of various usually long-haired breeds of dog reared to herd and guard sheep