Leeward Islands vs archipelago

Leeward Islands and archipelago both are nouns.

Word	Noun	Adjective	Verb	Adverb
Leeward Islands	Yes	No	No	No
archipelago	Yes	No	No	No

Leeward Islands (noun)	archipelago (noun)
a group of islands in the eastern West Indies	a group of many islands in a large body of water