Japanese cedar vs cedar

Japanese cedar and cedar both are nouns.

Word	Noun	Adjective	Verb	Adverb
Japanese cedar	Yes	No	No	No
cedar	Yes	No	No	No

As nouns, cedar is a hypernym of Japanese cedar; that is, cedar is a word with a broader meaning than Japanese cedar:

Japanese cedar: tall evergreen of Japan and China yielding valuable soft wood
cedar: any of numerous trees of the family Cupressaceae that resemble cedars

Other hypernyms of Japanese cedar include cedar tree.

Japanese cedar (noun)	cedar (noun)
tall evergreen of Japan and China yielding valuable soft wood	any cedar of the genus Cedrus
	any of numerous trees of the family Cupressaceae that resemble cedars
	durable aromatic wood of any of numerous cedar trees; especially wood of the red cedar often used for cedar chests