commence vs start

commence is not a noun while start is a noun.

Word	Noun	Adjective	Verb	Adverb
commence	No	No	Yes	No
start	Yes	No	Yes	No

As verbs, commence and start are synonyms defined as:

commence and start: take the first step or steps in carrying out an action

Other synonyms of commence include begin, get, get down, set about, set out, start out.

As verbs, commence and start are synonyms defined as:

Other synonyms of commence include begin, lead off.

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

As verbs, commence and start are synonyms defined as:

Other synonyms of commence include embark on, start up.

As verbs, start is a hypernym of commence; that is, start is a word with a broader meaning than commence:

Other hypernyms of commence include begin, commence, lead off.

commence (noun)	start (noun)
	the act of starting something
	a sudden involuntary movement
	a turn to be a starter (in a game at the beginning)
	the advantage gained by beginning early (as in a race)
	a signal to begin (as in a race)
	the beginning of anything
	a line indicating the location of the start of a race or a game
	the time at which something is supposed to begin

commence (verb)	start (verb)
take the first step or steps in carrying out an action	take the first step or steps in carrying out an action
set in motion, cause to start	set in motion, cause to start
get off the ground	play in the starting lineup
	bring into being
	get off the ground
	begin or set in motion
	get going or set in motion
	depart for someplace
	bulge outward
	move or jump suddenly, as if in surprise or alarm
	begin work or acting in a certain capacity, office or job
	begin an event that is implied and limited by the nature or inherent function of the direct object
	have a beginning, in a temporal, spatial, or evaluative sense
	have a beginning characterized in some specified way