sidebar vs news story

sidebar and news story both are nouns.

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

As nouns, news story is a hypernym of sidebar; that is, news story is a word with a broader meaning than sidebar:

Other hypernyms of sidebar include news article, newspaper article.

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