periodicity vs regularity

periodicity and regularity both are nouns.

Word	Noun	Adjective	Verb	Adverb
periodicity	Yes	No	No	No
regularity	Yes	No	No	No

As nouns, regularity is a hypernym of periodicity; that is, regularity is a word with a broader meaning than periodicity:

periodicity (noun)	regularity (noun)
the quality of recurring at regular intervals	the quality of being characterized by a fixed principle or rate
	a property of polygons: the property of having equal sides and equal angles