perpetuity vs sempiternity

perpetuity and sempiternity both are nouns.

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

As nouns, perpetuity and sempiternity are synonyms defined as:

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

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