fall out vs occur

fall out and occur both are verbs.

Word	Noun	Adjective	Verb	Adverb
fall out	No	No	Yes	No
occur	No	No	Yes	No

As verbs, fall out and occur are synonyms defined as:

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

fall out (verb)	occur (verb)
come to pass	come to pass
have a breach in relations	come to one's mind; suggest itself
drop out	to be found to exist
leave (a barracks) in order to take a place in a military formation, or leave a military formation
come as a logical consequence; follow logically