Upper Carboniferous vs Pennsylvanian period

Upper Carboniferous and Pennsylvanian period both are nouns.

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

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

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

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

Upper Carboniferous (noun)	Pennsylvanian period (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