Devonian vs Devonian period

Devonian and Devonian period both are nouns.

Word	Noun	Adjective	Verb	Adverb
Devonian	Yes	No	No	No
Devonian period	Yes	No	No	No

As nouns, Devonian and Devonian period are synonyms defined as:

Devonian and Devonian period: the period from 405 million to 345 million years ago; characterized by preponderance of fishes and appearance of amphibians and ammonites

Other synonyms of Devonian include Age of Fishes.

Devonian (noun)	Devonian period (noun)
the period from 405 million to 345 million years ago; characterized by preponderance of fishes and appearance of amphibians and ammonites	the period from 405 million to 345 million years ago; characterized by preponderance of fishes and appearance of amphibians and ammonites