Shetland Islands vs Shetland

Shetland Islands and Shetland both are nouns.

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

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

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

Other synonyms of Shetland Islands include Zetland.

Shetland Islands (noun)	Shetland (noun)
an archipelago of about 100 islands in the North Atlantic off the north coast of Scotland	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