overlap vs overlapping

overlap and overlapping both are nouns.

Word	Noun	Adjective	Verb	Adverb
overlap	Yes	No	Yes	No
overlapping	Yes	No	No	No

overlap (noun)	overlapping (noun)
a flap that lies over another part	covering with a design in which one element covers a part of another (as with tiles or shingles)
the property of partial coincidence in time
a representation of common ground between theories or phenomena

overlap (verb)	overlapping (verb)
extend over and cover a part of
coincide partially or wholly