First let's get a definition of who is the Mainstream Media that practices "bias".
"Mainstream media" consists of:
a)major television/radio news networks...i.e. ABC,CBS,NBC
b)major newspapers ... New York Times, WashingtonPost, two major papers
c)major magazines....NewsWeek, Time...
NOTE the exclusion of MSNBC,CNN,Fox,NPR as these are primarily editorial news and almost all do NOT
pretend to hide their bias. Fox being right/conservative/GOP, the rest.. left/progressive/democrat/liberals.
Now for the differentiation between NEWS and Editorial.
NOT my definition by the "professionals" journalism schools like Columbia.
Editorial
an article in a newspaper or other periodical or on a website presenting the opinion of the publisher, writer, or
editor.
the definition of editorial
News...
a report of recent events
Definition of NEWS
So true NEWS should be absent any opinion. Any personal observation.
In journalism classes students are taught:
Five Ws - Wikipedia
The
Five Ws,
- What happened?
- Who is involved?
- Where did it take place?
- When did it take place?
- Why did that happen?
The example will be coming later.
"Why" doesn't belong on this list. That's analysis, not news. News is simply who/what/where/when.
It's really very simple. News is a fact. "X" happened. Details -- "X" happened in place A, at time B, involving people C, D and E.
Editorial is opinion on why "X" happened, what it means that "X" happened, why it's a good or bad thing that "X" happened.
As far as your list CNN, NPR and Fox all have at least segments where they report straight news, as in real news. They're not necessarily always clear about which is which though. Particular example is when FNC is broadcasting Sean Hannity -- a commentator not a journalist -- while the logo "Fox News" sits in the corner. That's deliberately muddying the waters.
I don't know that NPR does editorials at all, though they will have talking heads on to analyze, as will pretty much everybody.
What you didn't mention here is another distinction that's rather critical, and that is: commercial vs noncommercial.
A commercial entity has as its incentive gathering listeners/viewers/readers. That biases it toward the sensational, because that's what sells those listeners/viewers/readers. That's why you'll see a thousand stories and shows on how Michael Jackson died and the OJ Simpson trial and nary a word about the government giving away vast tracts of broadcast real estate to giant corporations in TelComm 96.
That's got all kinds of implications. When a single entity whether it's NewsCorp, Viacom, Time Inc, whoever --- controls a vast network of television, radio, book publishing, newspaper publishing, movie productions, even sports teams and venues --- it very much gets to dictate what "the news" is, and what "the news" isn't . Especially if a sponsor doesn't like the way some program is going, e.g. Monsanto pressuring Fox to the point where Fox is telling its employees "we just paid umpteen million dollars for this station --
we'll tell
you what the news is. The news is what we say it is". And then there's the conflict of interest problem --- if you're GE and you're neck deep in military contracts and nuclear power, then your TV network NBC is not going to get a whole lot of leeway to cover Defense Department spending or nuclear power issues.
To name a couple.