eastern spruce vs Picea rubens

eastern spruce and Picea rubens both are nouns.

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

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

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

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

eastern 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