news report vs bulletin

news report and bulletin both are nouns.

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

As nouns, bulletin is a hyponym of news report; that is, bulletin is a word with a more specific, narrower meaning than news report:

news report: a short account of the news
bulletin: a brief report (especially an official statement issued for immediate publication or broadcast)

Other hyponyms of news report include newsletter, newssheet, communique, despatch, dispatch, urban legend, exclusive, scoop.

news report (noun)	bulletin (noun)
a short account of the news	a brief report (especially an official statement issued for immediate publication or broadcast)

news report (verb)	bulletin (verb)
	make public by bulletin