regard vs touch on

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

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

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

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

regard (noun)	touch on (noun)
a long fixed look
(usually preceded by `in') a detail or point
paying particular notice (as to children or helpless people)
an attitude of admiration or esteem
(usually plural) a polite expression of desire for someone's welfare
a feeling of friendship and esteem
the condition of being honored (esteemed or respected or well regarded)

regard (verb)	touch on (verb)
deem to be	restore by replacing a part or putting together what is torn or broken
look at attentively	have an effect upon
connect closely and often incriminatingly	refer to or discuss briefly
	be relevant to