Lanai Island vs Lanai

Lanai Island and Lanai both are nouns.

Word	Noun	Adjective	Verb	Adverb
Lanai Island	Yes	No	No	No
Lanai	Yes	No	No	No

As nouns, Lanai Island and Lanai are synonyms defined as:

Lanai Island and Lanai: an island of central Hawaii; a pineapple-growing area

Lanai Island (noun)	Lanai (noun)
an island of central Hawaii; a pineapple-growing area	an island of central Hawaii; a pineapple-growing area