come across vs see

come across is not a noun while see is a noun.

Word	Noun	Adjective	Verb	Adverb
come across	No	No	Yes	No
see	Yes	No	Yes	No

As verbs, come across and see are synonyms defined as:

Other synonyms of come across include encounter, meet, run across, run into.

come across (noun)	see (noun)
	the seat within a bishop's diocese where his cathedral is located

come across (verb)	see (verb)
be received or understood	deem to be
communicate the intended meaning or impression	perceive (an idea or situation) mentally
come together	get to know or become aware of, usually accidentally
be perceived in a certain way; make a certain impression	be careful or certain to do something; make certain of something
find unexpectedly	deliberate or decide
	make sense of; assign a meaning to
	find out, learn, or determine with certainty, usually by making an inquiry or other effort
	match or meet
	receive as a specified guest
	imagine; conceive of; see in one's mind
	come together
	conduct someone someplace
	perceive by sight or have the power to perceive by sight
	perceive or be contemporaneous with
	see or watch
	see and understand, have a good eye
	observe as if with an eye
	undergo or live through a difficult experience
	observe, check out, and look over carefully or inspect
	date regularly; have a steady relationship with
	go to see a place, as for entertainment
	go to see for professional or business reasons
	go to see for a social visit
	take charge of or deal with