Cornus amomum vs dogwood

Cornus amomum and dogwood both are nouns.

Word	Noun	Adjective	Verb	Adverb
Cornus amomum	Yes	No	No	No
dogwood	Yes	No	No	No

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

Cornus amomum: shrub of eastern North America having purplish stems and blue fruit
dogwood: a tree of shrub of the genus Cornus often having showy bracts resembling flowers

Other hypernyms of Cornus amomum include cornel, dogwood tree.

Cornus amomum (noun)	dogwood (noun)
shrub of eastern North America having purplish stems and blue fruit	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