come vs come up

come is a noun but come up is not a noun.

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

As verbs, come and come up are synonyms defined as:

come and come up: move toward, travel toward something or somebody or approach something or somebody

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

come (verb)	come up (verb)
come to pass; arrive, as in due course	result or issue
be found or available	start running, functioning, or operating
reach or enter a state, relation, condition, use, or position	gather or bring together
happen as a result	gather (money or other resources) together over time
have a certain priority	bring forth, usually something desirable
come to one's mind; suggest itself	come up, of celestial bodies
move toward, travel toward something or somebody or approach something or somebody	come to the surface
be received	move toward, travel toward something or somebody or approach something or somebody
cover a certain distance	move upward
reach a destination; arrive by movement or progress	get something or somebody for a specific purpose
experience orgasm	originate or come into being
come under, be classified or included	be mentioned
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