Western Islands vs Western Isles

Western Islands and Western Isles both are nouns.

Word	Noun	Adjective	Verb	Adverb
Western Islands	Yes	No	No	No
Western Isles	Yes	No	No	No

As nouns, Western Islands and Western Isles are synonyms defined as:

Western Islands and Western Isles: a group of more than 500 islands off the western coast of Scotland

Other synonyms of Western Islands include Hebridean Islands, Hebridean Isles, Hebrides.

Western Islands (noun)	Western Isles (noun)
a group of more than 500 islands off the western coast of Scotland	a group of more than 500 islands off the western coast of Scotland