Japanese vs geisha

Japanese and geisha both are nouns.

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

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

Japanese: a native or inhabitant of Japan
geisha: a Japanese woman trained to entertain men with conversation and singing and dancing

Other hyponyms of Japanese include Ryukyuan, Jap, Nip, geisha girl, shogun.

Japanese (noun)	geisha (noun)
the language (usually considered to be Altaic) spoken by the Japanese	a Japanese woman trained to entertain men with conversation and singing and dancing
a native or inhabitant of Japan

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