sempiternity vs perpetuity

sempiternity and perpetuity both are nouns.

Word	Noun	Adjective	Verb	Adverb
sempiternity	Yes	No	No	No
perpetuity	Yes	No	No	No

As nouns, sempiternity and perpetuity are synonyms defined as:

sempiternity and perpetuity: the property of being perpetual (seemingly ceaseless)

sempiternity (noun)	perpetuity (noun)
the property of being perpetual (seemingly ceaseless)	the property of being perpetual (seemingly ceaseless)