report vs bulletin

report and bulletin both are nouns.

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

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

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

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

report (noun)	bulletin (noun)
the general estimation that the public has for a person	a brief report (especially an official statement issued for immediate publication or broadcast)
a short account of the news
the act of informing by verbal report
an essay (especially one written as an assignment)
a written document describing the findings of some individual or group
a written evaluation of a student's scholarship and deportment
a sharp explosive sound (especially the sound of a gun firing)

report (verb)	bulletin (verb)
to give an account or representation of in words	make public by bulletin
make known to the authorities
complain about; make a charge against
announce one's presence
announce as the result of an investigation or experience or finding
be responsible for reporting the details of, as in journalism