Japanese Islands vs Hokkaido

Japanese Islands and Hokkaido both are nouns.

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

Japanese Islands (noun)	Hokkaido (noun)
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 second largest of the four main islands of Japan; to the north of Honshu