patching vs mending

patching and mending both are nouns.

Word	Noun	Adjective	Verb	Adverb
patching	Yes	No	No	No
mending	Yes	No	No	No

As nouns, mending is a hypernym of patching; that is, mending is a word with a broader meaning than patching:

Other hypernyms of patching include fix, fixing, fixture, mend, repair, reparation.

patching (noun)	mending (noun)
the act of mending a hole in a garment by sewing a patch over it	the act of putting something in working order again
	garments that must be repaired