commence vs set off

commence and set off both are verbs.

Word	Noun	Adjective	Verb	Adverb
commence	No	No	Yes	No
set off	No	No	Yes	No

As verbs, set off is a hyponym of commence; that is, set off is a word with a more specific, narrower meaning than commence:

commence (verb)	set off (verb)
take the first step or steps in carrying out an action	cause to burst with a violent release of energy
set in motion, cause to start	set in motion or cause to begin
get off the ground	direct attention to, as if by means of contrast
	provoke or stir up
	put in motion or move to act
	depart for someplace
	make up for