capital of Japan vs Japan

capital of Japan and Japan both are nouns.

Word	Noun	Adjective	Verb	Adverb
capital of Japan	Yes	No	No	No
Japan	Yes	No	No	No

capital of Japan (noun)	Japan (noun)
the capital and largest city of Japan; the economic and cultural center of Japan	a constitutional monarchy occupying the Japanese Archipelago; a world leader in electronics and automobile manufacture and ship building
	a string of more than 3,000 islands to the east of Asia extending 1,300 miles between the Sea of Japan and the western Pacific Ocean