Devonian period vs Devonian

Devonian period and Devonian both are nouns.

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

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

Devonian period and Devonian: 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 period include Age of Fishes.

Devonian period (noun)	Devonian (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