common white dogwood vs dogwood

common white dogwood and dogwood both are nouns.

Word	Noun	Adjective	Verb	Adverb
common white dogwood	Yes	No	No	No
dogwood	Yes	No	No	No

As nouns, dogwood is a hypernym of common white dogwood; that is, dogwood is a word with a broader meaning than common white dogwood:

common white dogwood: deciduous tree; celebrated for its large white or pink bracts and stunning autumn color that is followed by red berries
dogwood: a tree of shrub of the genus Cornus often having showy bracts resembling flowers

Other hypernyms of common white dogwood include cornel, dogwood tree.

common white dogwood (noun)	dogwood (noun)
deciduous tree; celebrated for its large white or pink bracts and stunning autumn color that is followed by red berries	a tree of shrub of the genus Cornus often having showy bracts resembling flowers
	hard tough wood of any dogwood of the genus Cornus; resembles boxwood