Shetland vs Shetland Islands

Shetland and Shetland Islands both are nouns.

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

As nouns, Shetland and Shetland Islands are synonyms defined as:

Shetland and Shetland Islands: an archipelago of about 100 islands in the North Atlantic off the north coast of Scotland

Other synonyms of Shetland include Zetland.

Shetland (noun)	Shetland Islands (noun)
a small sheepdog resembling a collie that was developed in the Shetland Islands	an archipelago of about 100 islands in the North Atlantic off the north coast of Scotland
an archipelago of about 100 islands in the North Atlantic off the north coast of Scotland