Japan vs prefecture

Japan and prefecture both are nouns.

Word	Noun	Adjective	Verb	Adverb
Japan	Yes	No	No	No
prefecture	Yes	No	No	No

Japan (noun)	prefecture (noun)
a constitutional monarchy occupying the Japanese Archipelago; a world leader in electronics and automobile manufacture and ship building	the office of prefect
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	the district administered by a prefect (as in France or Japan or the Roman Empire)