Japanese tree lilac vs lilac

Japanese tree lilac and lilac both are nouns.

Word	Noun	Adjective	Verb	Adverb
Japanese tree lilac	Yes	No	No	No
lilac	Yes	Yes	No	No

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

Japanese tree lilac: small tree of Japan having narrow pointed leaves and creamy-white flowers
lilac: any of various plants of the genus Syringa having large panicles of usually fragrant flowers

Japanese tree lilac (noun)	lilac (noun)
small tree of Japan having narrow pointed leaves and creamy-white flowers	any of various plants of the genus Syringa having large panicles of usually fragrant flowers

Japanese tree lilac (adjective)	lilac (adjective)
	of a pale purple color