Rhus glabra vs sumac

Rhus glabra and sumac both are nouns.

Word	Noun	Adjective	Verb	Adverb
Rhus glabra	Yes	No	No	No
sumac	Yes	No	No	No

As nouns, sumac is a hypernym of Rhus glabra; that is, sumac is a word with a broader meaning than Rhus glabra:

Rhus glabra: common nonpoisonous shrub of eastern North America with waxy compound leaves and green paniculate flowers followed by red berries
sumac: a shrub or tree of the genus Rhus (usually limited to the non-poisonous members of the genus)

Other hypernyms of Rhus glabra include shumac, sumach.

Rhus glabra (noun)	sumac (noun)
common nonpoisonous shrub of eastern North America with waxy compound leaves and green paniculate flowers followed by red berries	a shrub or tree of the genus Rhus (usually limited to the non-poisonous members of the genus)
	wood of a sumac