darn vs touch on

darn is a noun but touch on is not a noun.

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

As verbs, touch on is a hypernym of darn; that is, touch on is a word with a broader meaning than darn:

darn: repair by sewing
touch on: restore by replacing a part or putting together what is torn or broken

Other hypernyms of darn include bushel, doctor, fix, furbish up, mend, repair, restore.

darn (noun)	touch on (noun)
sewing that repairs a worn or torn hole (especially in a garment)
something of little value

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