White knights had literally nothing to do with incels. They existed side by side and hated each other.
White knights are people who always stick up for the woman and look at her like a victim no matter what. A woman could cheat on her boyfriend and a white knight would only say "It's okay; he didn't give you enough attention. In fact, he's a pig or else he'd be more sympathetic. After all, he pushed you to cheat on him. And tbh, it's kind of misogynistic that he was just expecting you to only have sex with him. Monogamy is patriarchy."
Incels, by contrast, are the opposite. No matter what, they always believe the woman is evil. A woman could be getting beat and they'd just ask what she did to deserve it.
Tbh I hate them both equally. Neither of them acknowledge that women are just people, capable of being either nice or shitty.