I think the difference is the phoniness. The BH women don't even bother to keep track of who they're supposed to be mad at, even within a particular episode. The controversies are manufactured, so it's harder for them to remember how they reacted back then, how they're supposed to feel now. So if they're constantly flip-flopping, we can't be expected to keep up.
There's not as much flip-flopping on NY. Plus, NY carries their crap from year to year, despite all the "moving on" promises. BH pretends to move on, so we end up confused when they don't.
This episode was a not mess. None of them could be honest from minute to minute. No one took time to think -- they just reacted, and they reacted by echoing what the person next to them was doing/saying.
Except for Denise, with that wonderful comeback to Camille. "No, YOU shut the fuck up!" Camille is a vapid, useless waste of space. Why did David marry her?