rotundity vs sphericity

rotundity and sphericity both are nouns.

Word	Noun	Adjective	Verb	Adverb
rotundity	Yes	No	No	No
sphericity	Yes	No	No	No

As nouns, rotundity and sphericity are synonyms defined as:

Other synonyms of rotundity include globosity, globularness, rotundness, sphericalness.

rotundity (noun)	sphericity (noun)
the roundness of a 3-dimensional object	the roundness of a 3-dimensional object
the fullness of a tone of voice