Indonesian vs Javan

Indonesian and Javan both are nouns.

Word	Noun	Adjective	Verb	Adverb
Indonesian	Yes	Yes	No	No
Javan	Yes	Yes	No	No

As nouns, Javan is a hyponym of Indonesian; that is, Javan is a word with a more specific, narrower meaning than Indonesian:

Other hyponyms of Indonesian include Sumatran, Papuan, Javanese.

Indonesian (noun)	Javan (noun)
the dialect of Malay used as the national language of the Republic of Indonesia or of Malaysia	a native or inhabitant of Java
a native or inhabitant of Indonesia

Indonesian (adjective)	Javan (adjective)
of or relating to or characteristic of Indonesia or its people or languages	of or relating to or characteristic of Java or its inhabitants or its language