/r/politics is a subforum on a news aggregator. While media organizations definitely buy upvotes, as of yet there's no actual evidence of Reddit itself artificially promoting/demoting content
within a subreddit(Tweaking the algorithm to get bot-propogated t_d content off the front page doesn't count, it's a different subforum)
Brietbart is an entirely different category than Fox news. It will publish straight up conspiracy theories with no evidence. I'm talking "moon landing didn't happen" level shit. It's an insult to tabloids, to call it a tabloids.
Fox News is so comically biased to compare it to CNN is dishonest. CNN has liberal bias, sure, but it doesnt sink to the level of claiming Hillary Clinton had Seth rich assassinated (https://www.politifact.com/punditfact/statements/2017/may/23...) or completely makes shit up about supreme court candidates whole-cloth (https://www.politifact.com/punditfact/statements/2016/mar/18...).
Sure, they're gonna spend a lot of airtime on the "kavanaugh allegedly raped a girl in high school" story, or when the president says some messed up ish they're gonna go ahead and play that clip again and again, but that is a far cry from outright lying, which fox news does again and again, and which Breitbart does every breath.