Japan vs Honshu

Japan and Honshu both are nouns.

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

Japan (noun)	Honshu (noun)
a constitutional monarchy occupying the Japanese Archipelago; a world leader in electronics and automobile manufacture and ship building	the central and largest of the four main islands of Japan; between the Sea of Japan and the Pacific Ocean; regarded as the Japanese mainland
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