Cinnamomum cassia vs cassia

Cinnamomum cassia and cassia both are nouns.

Word	Noun	Adjective	Verb	Adverb
Cinnamomum cassia	Yes	No	No	No
cassia	Yes	No	No	No

As nouns, Cinnamomum cassia and cassia are synonyms defined as:

Cinnamomum cassia and cassia: Chinese tree with aromatic bark; yields a less desirable cinnamon than Ceylon cinnamon

Other synonyms of Cinnamomum cassia include cassia-bark tree.

Cinnamomum cassia (noun)	cassia (noun)
Chinese tree with aromatic bark; yields a less desirable cinnamon than Ceylon cinnamon	any of various trees or shrubs of the genus Cassia having pinnately compound leaves and usually yellow flowers followed by long seedpods
	Chinese tree with aromatic bark; yields a less desirable cinnamon than Ceylon cinnamon