The following is how it gets interpreted by a lot of people and has no connection whatsoever to my own opinions of these two people:
Clinton having an affair with an intern was seen as bad because of the infidelity, but at the same time it makes him look virile and manly. It’s a mixed bag but he comes out looking pretty good overall.
An intern having an affair with Clinton is bad because it makes her a slut and she should have resisted her carnal urges. And she had an affair with a married man, so she’s a home wrecker too! There’s no positive aspect to this at all, and it’s all her fault for not behaving. And then her misbehavior gets plastered all over the national news, and she gets the shaming she deserves!