red spruce vs Picea rubens

red spruce and Picea rubens both are nouns.

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

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

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

Other synonyms of red spruce include eastern spruce, yellow spruce.

red spruce (noun)	Picea rubens (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