Shetland Islands vs Zetland

Shetland Islands and Zetland both are nouns.

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

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

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

Other synonyms of Shetland Islands include Shetland.

Shetland Islands (noun)	Zetland (noun)
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