Tokyo vs Japanese capital

Tokyo and Japanese capital both are nouns.

Word	Noun	Adjective	Verb	Adverb
Tokyo	Yes	No	No	No
Japanese capital	Yes	No	No	No

As nouns, Tokyo and Japanese capital are synonyms defined as:

Tokyo and Japanese capital: the capital and largest city of Japan; the economic and cultural center of Japan

Other synonyms of Tokyo include capital of Japan, Edo, Tokio, Yeddo, Yedo.

Tokyo (noun)	Japanese capital (noun)
the capital and largest city of Japan; the economic and cultural center of Japan	the capital and largest city of Japan; the economic and cultural center of Japan