touch on vs involve

touch on and involve both are verbs.

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

As verbs, involve is a hyponym of touch on; that is, involve is a word with a more specific, narrower meaning than touch on:

touch on (verb)	involve (verb)
restore by replacing a part or putting together what is torn or broken	make complex or intricate or complicated
have an effect upon	occupy or engage the interest of
refer to or discuss briefly	have as a necessary feature
be relevant to	connect closely and often incriminatingly
	contain as a part
	engage as a participant
	require as useful, just, or proper