Reading the entry - it isn't. It's basically the same thing.

What is different in germany, though, is that the discussion here revolves around forcing private sector enterprises to have specific (government set) quota of women in their leadership (or else be punished by the law).

Affirmative action in the US seems to revolve more around not negatively discriminating against women when making hiring decisions, but not forcing government set quotas on companies.

I can't quite imagine the US government interfering with private enterprise in this way.