occur vs come about

occur and come about both are verbs.

Word	Noun	Adjective	Verb	Adverb
occur	No	No	Yes	No
come about	No	No	Yes	No

As verbs, occur and come about are synonyms defined as:

Other synonyms of occur include fall out, go on, hap, happen, pass, pass off, take place.

occur (verb)	come about (verb)
come to pass	come to pass
come to one's mind; suggest itself
to be found to exist