Picea rubens vs red spruce

Picea rubens and red spruce both are nouns.

Word	Noun	Adjective	Verb	Adverb
Picea rubens	Yes	No	No	No
red spruce	Yes	No	No	No

As nouns, Picea rubens and red spruce are synonyms defined as:

Picea rubens and red spruce: medium-sized spruce of eastern North America; chief lumber spruce of the area; source of pulpwood

Other synonyms of Picea rubens include eastern spruce, yellow spruce.

Picea rubens (noun)	red spruce (noun)
medium-sized spruce of eastern North America; chief lumber spruce of the area; source of pulpwood	medium-sized spruce of eastern North America; chief lumber spruce of the area; source of pulpwood