Fox is biased, CNN is a thoroughly discredited disinformation network. That's the difference.
All the BS on CNN about Russian collusion, women have to be believed unless they're accusing leftists, Suleimani was a beloved father figure, Trump has no apparent strategy in the ME, Trump slipped on a ramp so he must be senile, Trump is senile but Biden is fine, Trump asked for a favour and then talked about Burisma, Trump called veterans losers, Trump invented kid cages, women were forced to drink from toilets, M Brown was a gentle giant, Brionna was a sleeping beauty, Rayshard was shot for running away, cops are committing genocide against blacks, asking voters for ID is racist, mail-in ballots are impervious to fraud and signature-verification is an attempt to disenfranchise Demmies, walls are racist and they don't work, all whites are guilty of systemic racism, Biden did nothing wrong in Ukraine, Trump referred to immigrants as animals, riots were peaceful, etc is unrivalled on Fox News. Fox has no equivalent level of bullshit stories to match up with that. Not even close.
Plus CNN got busted for cheating on the debate between Trump & Hillary and they were successfully sued for defamation of character by a high school kid.