touch on vs improve

touch on and improve both are verbs.

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

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

touch on: restore by replacing a part or putting together what is torn or broken
improve: to make better

Other hypernyms of touch on include ameliorate, amend, better, meliorate.

touch on (verb)	improve (verb)
restore by replacing a part or putting together what is torn or broken	get better
have an effect upon	to make better
refer to or discuss briefly
be relevant to