Shetland vs sheepdog

Shetland and sheepdog both are nouns.

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

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

Shetland: a small sheepdog resembling a collie that was developed in the Shetland Islands
sheepdog: any of various usually long-haired breeds of dog reared to herd and guard sheep

Other hypernyms of Shetland include sheep dog, shepherd dog.

Shetland (noun)	sheepdog (noun)
a small sheepdog resembling a collie that was developed in the Shetland Islands	any of various usually long-haired breeds of dog reared to herd and guard sheep
an archipelago of about 100 islands in the North Atlantic off the north coast of Scotland