In-group fighting/insults is never looked at the same way as out-of-group fighting/insults.
As an example, imagine a professional baseball game. If two players on the same team fight, the other team stays out of it. Their own team will either let them fight or break it up, but they most likely won't join in and make it a general melee. Fighting within the same group is a fight between INDIVIDUALS and treated as such. Now, same scenario but the players on are different teams. Even if the exact same thing caused the fight, now the benches are cleared because two people fighting is suddenly a fight between GROUPS.
Barr's problem is no matter how you look at it, it was an out-of-group fight. Particularly with the racist overtones, it became a group fight and those hosting her show had no intention of clearing the benches with her.
Samantha's slur is a woman using a slur against women to "fight" another woman. Those who view it through that lens will see it as an in-group fight, thus between individuals, and see no hypocrisy in Roseanne being treated more severely. Being crude and hateful toward an individual is a lesser offense than being crude and hateful toward an entire group, so the social punishment is less (particularly if you can justify the victim "deserving" it). Those who view it as a political attack will view it as an out-of-group "fight" and see no difference, they're still ready to clear the benches. If Roseanne was black, I think the response (if any) to her tweet would have been much more subdued. And if Samantha were a man, a harsher response to her skit/speech/whatever. As it stands, Roseanne is stuck with an out-of-group and Bee has people in the debate with both perspectives. People will see a legitimate difference or a contrived one based on which perspective they have.
Something to consider... I think this is mostly right, except that the grouping around Samatha Bee is more political. It's true enough that woman-to-woman alone isn't going to clear the benches. But that's not the predominant grouping. It's ideological fringes, with the sane middle kinda siding with one or the other. In the case of Bar, the fringe right is with her, the fringe left is against her--that dynamic is unchanging. The middle sided against Bar because they see her as disparaging a group. Whether she did or didn't is at least a little nuanced, but not enough to split the middle.
With Bee, the grouping is again with the same fringes taking the obvious sides, but this time the middle is more aligned against bee. People aren't outraged because a woman called another woman a ****. They're outraged because a personality on a network show called the president's daughter a ****.
Of course the middle is a little more split over Bee than they were over Roseanne Bar. But I think that has more to do with the middle left's popular membership in #resist. However it appears that most of the middle are not with Bee. And several advertisers have pulled their ads from her show. But in her case, there's not a network exec loathing her popularity, eager to find an excuse to fire her, like there was with Roseanne.
The big question is, is there hypocrisy in all of this? Well, not with the sane middle. It seems to me they've picked the socially consistent sides both times. But I'd say that there is evident hypocrisy in both fringes. Flip the circumstances and both fringes will reliably flip the words.