cornel vs red osier

cornel and red osier both are nouns.

Word	Noun	Adjective	Verb	Adverb
cornel	Yes	No	No	No
red osier	Yes	No	No	No

As nouns, red osier is a hyponym of cornel; that is, red osier is a word with a more specific, narrower meaning than cornel:

cornel: a tree of shrub of the genus Cornus often having showy bracts resembling flowers
red osier: common North American shrub with reddish purple twigs and white flowers

cornel (noun)	red osier (noun)
a tree of shrub of the genus Cornus often having showy bracts resembling flowers	Eurasian osier having reddish or purple twigs and bark rich in tannin
	common North American shrub with reddish purple twigs and white flowers