collie vs sheepdog

collie and sheepdog both are nouns.

Word	Noun	Adjective	Verb	Adverb
collie	Yes	No	No	No
sheepdog	Yes	No	No	No

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

collie: a silky-coated sheepdog with a long ruff and long narrow head developed in Scotland
sheepdog: any of various usually long-haired breeds of dog reared to herd and guard sheep

Other hypernyms of collie include sheep dog, shepherd dog.

collie (noun)	sheepdog (noun)
a silky-coated sheepdog with a long ruff and long narrow head developed in Scotland	any of various usually long-haired breeds of dog reared to herd and guard sheep