trigger vs touch off

trigger is a noun but touch off is not a noun.

Word	Noun	Adjective	Verb	Adverb
trigger	Yes	No	Yes	No
touch off	No	No	Yes	No

As verbs, trigger and touch off are synonyms defined as:

Other synonyms of trigger include activate, actuate, set off, spark, spark off, trigger off, trip.

trigger (noun)	touch off (noun)
an act that sets in motion some course of events
lever that activates the firing mechanism of a gun
a device that activates or releases or causes something to happen

trigger (verb)	touch off (verb)
release or pull the trigger on	put in motion or move to act
put in motion or move to act