come on vs come

come on is not a noun while come is a noun.

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

As verbs, come is a hypernym of come on; that is, come is a word with a broader meaning than come on:

come on: move towards
come: move toward, travel toward something or somebody or approach something or somebody

Other hypernyms of come on include come up.

come on (noun)	come (noun)
	the thick white fluid containing spermatozoa that is ejaculated by the male genital tract

come on (verb)	come (verb)
occur or become available	come to pass; arrive, as in due course
appear or become visible; make a showing	be found or available
develop in a positive way	reach or enter a state, relation, condition, use, or position
start running, functioning, or operating	happen as a result
move towards	have a certain priority
	come to one's mind; suggest itself
	move toward, travel toward something or somebody or approach something or somebody
	be received
	cover a certain distance
	reach a destination; arrive by movement or progress
	experience orgasm
	come under, be classified or included
	proceed or get along
	extend or reach
	to be the product or result
	exist or occur in a certain point in a series
	be a native of
	to measure up to in kind or quality
	add up in number or quantity
	come forth
	come from; be connected by a relationship of blood, for example