Nihon vs Japanese

Nihon and Japanese both are nouns.

Word	Noun	Adjective	Verb	Adverb
Nihon	Yes	No	No	No
Japanese	Yes	Yes	No	No

Nihon (noun)	Japanese (noun)
a constitutional monarchy occupying the Japanese Archipelago; a world leader in electronics and automobile manufacture and ship building	the language (usually considered to be Altaic) spoken by the Japanese
	a native or inhabitant of Japan

Nihon (adjective)	Japanese (adjective)
	of or relating to or characteristic of Japan or its people or their culture or language