I don't know. I think he works a LOT more consistently and often than she does. He basically doesn't stop working.
But she is respected, obviously better known in the US and world, as O'Brien is a TV star in Britain. Most importantly, though she has a strong, often indie career of her choosing, despite being shied away from after "Brown Bunny" by some execs.
I love that her career is on her terms, though, and yes, it's fair to say it wasn't destroyed because she gave a real blowjob, while fully clothed, in the film.
I'm not sure that would be true for a man and explicit nudity, sex, and on-screen ejaculation, like O'Brien did, in America. That film is extremely explicit, for the full running length with multiple forms of sex and genitalia/penetration/ejaculation close-ups. So different from BB in that way, and of course we always can forgive a sexualized woman if we want to (after tsk, tsking) in America, whereas we have such a complicated history with the male nude.
I really do think his mainstream success before and after is a unique thing, but the point about Sevigny is fair, too. The key differentiator for me, though, is she is still asked about it all the time—asked to explain and defend the choice. I saw a recent interview with her where she flat out said she's tired of talking about it and doesn't feel the need to after all these years, even if people keep asking.
Whereas it doesn't come up for/with O'Brien nearly as often or regularly, though it does come up. Most of the time, it's simply treated as one of many things he's done in his past, that may or may not be relevant to the current interview. That's an amazing feat for a British actor, and I'm not sure an American actor could pull it off.