Shetland vs Zetland

Shetland and Zetland both are nouns.

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

As nouns, Shetland and Zetland are synonyms defined as:

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

Other synonyms of Shetland include Shetland Islands.

Shetland (noun)	Zetland (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