news bulletin vs newsflash

news bulletin and newsflash both are nouns.

Word	Noun	Adjective	Verb	Adverb
news bulletin	Yes	No	No	No
newsflash	Yes	No	No	No

As nouns, news bulletin and newsflash are synonyms defined as:

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

Other synonyms of news bulletin include flash, newsbreak.

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