red dogwood vs American dogwood

red dogwood and American dogwood both are nouns.

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

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

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

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

red dogwood (noun)	American 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