news story vs sidebar

news story and sidebar both are nouns.

Word	Noun	Adjective	Verb	Adverb
news story	Yes	No	No	No
sidebar	Yes	No	No	No

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

Other hyponyms of news story include lead, lead story, personal.

news story (noun)	sidebar (noun)
an article reporting news	(law) a courtroom conference between the lawyers and the judge that is held out of the jury's hearing
	a short news story presenting sidelights on a major story