spark vs touch off

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

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

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

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

spark (noun)	touch off (noun)
merriment expressed by a brightness or gleam or animation of countenance
a momentary flash of light
a small fragment of a burning substance thrown out by burning material or by friction
electrical conduction through a gas in an applied electric field
a small but noticeable trace of some quality that might become stronger

spark (verb)	touch off (verb)
put in motion or move to act	put in motion or move to act
emit or produce sparks