For example take 'the revoking of Brennan's security clearance'. A lot, if not all, news outlets will have those words in the title. So SPIDR takes the newest article about this [cbs] as the title and lists (at this moment 36minutes ago) 71 articles from other news outlets in order of time which match this. For the US and this issue it would have CNN, ABC, CBS, the guardian, RT, brreithart, the week, washinton post (and more) dating back 18 hours ago. A list may feature mutiple articles from one news outlet (let's say CNN) if they wrote mutiple articles about it, usually this is the case with 'developing' stories.

It sometimes goes wrong with the more local stories which feature 'man kills bla bla bla' because those kind of articles a look alike text wise. (So different cases are grouped together)

And I wonder if this site selects stories that promote the same agenda or narrative, or if there are opposing viewpoints presented.

But in the case of Brennan, even opinion pieces would feature Brennan, Trump, security, clearance if they agree or disagree. Breitbart, CNN, Fox, ABC, CBS are featured.