Women are more likely to think that their success is a fluke. Even if they have sustained success, they are more likely to think it is a fluke. When they fail at something, women are more likely to think it is due to their own failings. Women are more than twice as likely to get depressed over their failures - indeed, Susan Pinker calls the connection between women feeling like an imposter and getting depressed "the other problem with no name."
Men are more prone to overestimate their own skills. They are more likely to bluff, and take on responsibilities they are not really ready for. When they fail, they are likely to blame other people or outside conditions.
Reality is still reality, and offers a real bottom line of whether we succeed or not. However, men and women still draw different conclusions from the verdict that reality renders.
Men are more likely to see failures as investments from which they can learn, and to regard challenges ahead as something they can probably overcome. Because of the way women regard their own talents, even their own achievements, they are likely to aim lower than men. This has a cumulative effect. Imposter syndrome, as Pinker calls it, is one of the factors that means there are fewer women at the top of our power hierarchies than there are men.