Pennsylvanian period vs Upper Carboniferous

Pennsylvanian period and Upper Carboniferous both are nouns.

Word	Noun	Adjective	Verb	Adverb
Pennsylvanian period	Yes	No	No	No
Upper Carboniferous	Yes	No	No	No

As nouns, Pennsylvanian period and Upper Carboniferous are synonyms defined as:

Pennsylvanian period and Upper Carboniferous: the period from 310 million to 280 million years ago; characterized by warm climate and swampy land

Other synonyms of Pennsylvanian period include Pennsylvanian, Upper Carboniferous period.

Pennsylvanian period (noun)	Upper Carboniferous (noun)
the period from 310 million to 280 million years ago; characterized by warm climate and swampy land	the period from 310 million to 280 million years ago; characterized by warm climate and swampy land