Honshu vs Japanese Islands

Honshu and Japanese Islands both are nouns.

Word	Noun	Adjective	Verb	Adverb
Honshu	Yes	No	No	No
Japanese Islands	Yes	No	No	No

Honshu (noun)	Japanese Islands (noun)
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