come vs come on

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

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

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

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

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

come (verb)	come on (verb)
come to pass; arrive, as in due course	occur or become available
be found or available	appear or become visible; make a showing
reach or enter a state, relation, condition, use, or position	develop in a positive way
happen as a result	start running, functioning, or operating
have a certain priority	move towards
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