open up vs fly open

open up and fly open both are verbs.

Word	Noun	Adjective	Verb	Adverb
open up	No	No	Yes	No
fly open	No	No	Yes	No

As verbs, fly open is a hyponym of open up; that is, fly open is a word with a more specific, narrower meaning than open up:

Other hyponyms of open up include unfasten.

open up (verb)	fly open (verb)
make available	come open suddenly
become available
talk freely and without inhibition
cause to open or to become open
become open
open up an area or prepare a way
start to operate or function or cause to start operating or functioning