great gray owl vs Strix nebulosa

great gray owl and Strix nebulosa both are nouns.

Word	Noun	Adjective	Verb	Adverb
great gray owl	Yes	No	No	No
Strix nebulosa	Yes	No	No	No

As nouns, great gray owl and Strix nebulosa are synonyms defined as:

great gray owl and Strix nebulosa: large dish-faced owl of northern North America and western Eurasia

Other synonyms of great gray owl include great grey owl.

great gray owl (noun)	Strix nebulosa (noun)
large dish-faced owl of northern North America and western Eurasia	large dish-faced owl of northern North America and western Eurasia