red dogwood vs red osier dogwood

red dogwood and red osier dogwood both are nouns.

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

As nouns, red dogwood and red osier dogwood are synonyms defined as:

red dogwood and red osier dogwood: common North American shrub with reddish purple twigs and white flowers

Other synonyms of red dogwood include American dogwood, Cornus stolonifera, red osier, redbrush.

red dogwood (noun)	red osier dogwood (noun)
common North American shrub with reddish purple twigs and white flowers	common North American shrub with reddish purple twigs and white flowers
European deciduous shrub turning red in autumn having dull white flowers