apply vs touch on

apply and touch on both are verbs.

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

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

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

apply (verb)	touch on (verb)
ask (for something)	restore by replacing a part or putting together what is torn or broken
refer (a word or name) to a person or thing	have an effect upon
put into service; make work or employ for a particular purpose or for its inherent or natural purpose	refer to or discuss briefly
coat, cover or smear a surface with	be relevant to
give or convey physically
avail oneself to
ensure observance of laws and rules
apply oneself to
be pertinent or relevant or applicable
be applicable to; as to an analysis