archipelago vs Tubuai Islands

archipelago and Tubuai Islands both are nouns.

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

archipelago (noun)	Tubuai Islands (noun)
a group of many islands in a large body of water	a chain of small islands in French Polynesia