start vs come on

start is a noun but come on is not a noun.

Word	Noun	Adjective	Verb	Adverb
start	Yes	No	Yes	No
come on	No	No	Yes	No

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

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

Other hyponyms of start include come up, go on, get off the ground, take off.

start (noun)	come on (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

start (verb)	come on (verb)
take the first step or steps in carrying out an action	occur or become available
set in motion, cause to start	appear or become visible; make a showing
play in the starting lineup	develop in a positive way
bring into being	start running, functioning, or operating
get off the ground	move towards
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