I'm going to cheat and say the biggest difference is how delusional they are.
I didn't follow the gaf side of things, but I don't recall them claiming to be anything other than a circle jerk of moderators banning people that disagree with them. ResetEra seems to be genuinely surprised when their prominent black posters turn out to be racist white guys, or when their attempt at review bombing turns out to be so flaccid that it has no real impact. They are always complaining about the nazis infesting the forum without once looking in a mirror.
Their whole cancel culture mentality is a great example. People like Joe Rogan and PewDiePie aren't allowed to be linked, as if their insignificant forum can take down 2 of the biggest YouTube celebrities simply by not linking their content. They are willing to launch harassment campaigns, review bombs, and drive people to suicide over a throw away tweet from 8 years ago, only to be caught completely off guard when the wider gaming internet shuns them for that behavior.