touch on vs come to

touch on and come to both are verbs.

Word	Noun	Adjective	Verb	Adverb
touch on	No	No	Yes	No
come to	No	No	Yes	No

As verbs, touch on and come to are synonyms defined as:

Other synonyms of touch on include bear on, concern, have to do with, pertain, refer, relate, touch.

touch on (verb)	come to (verb)
restore by replacing a part or putting together what is torn or broken	return to consciousness
have an effect upon	cause to experience suddenly
refer to or discuss briefly	attain
be relevant to	be relevant to