newsflash vs newsbreak

newsflash and newsbreak both are nouns.

Word	Noun	Adjective	Verb	Adverb
newsflash	Yes	No	No	No
newsbreak	Yes	No	No	No

As nouns, newsflash and newsbreak are synonyms defined as:

newsflash and newsbreak: a short news announcement concerning some on-going news story

Other synonyms of newsflash include flash, news bulletin.

newsflash (noun)	newsbreak (noun)
a short news announcement concerning some on-going news story	a short news announcement concerning some on-going news story