Japanese language vs Nippon

Japanese language and Nippon both are nouns.

Word	Noun	Adjective	Verb	Adverb
Japanese language	Yes	No	No	No
Nippon	Yes	No	No	No

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