touch on vs mend

touch on is not a noun while mend is a noun.

Word	Noun	Adjective	Verb	Adverb
touch on	No	No	Yes	No
mend	Yes	No	Yes	No

As verbs, touch on and mend are synonyms defined as:

touch on and mend: restore by replacing a part or putting together what is torn or broken

Other synonyms of touch on include bushel, doctor, fix, furbish up, repair, restore.

touch on (noun)	mend (noun)
	the act of putting something in working order again
	sewing that repairs a worn or torn hole (especially in a garment)

touch on (verb)	mend (verb)
restore by replacing a part or putting together what is torn or broken	restore by replacing a part or putting together what is torn or broken
have an effect upon	heal or recover
refer to or discuss briefly
be relevant to