Solomon Islands vs Melanesia

Solomon Islands and Melanesia both are nouns.

Word	Noun	Adjective	Verb	Adverb
Solomon Islands	Yes	No	No	No
Melanesia	Yes	No	No	No

Solomon Islands (noun)	Melanesia (noun)
the southern Solomon Islands that since 1978 form an independent state in the British Commonwealth	the islands in the southwestern part of Oceania
the northernmost islands are part of Papua New Guinea; the remainder form an independent state within the British Commonwealth