Female competition is when you are with a guy you like and you look around, see a girl who is prettier than you standing nearby, and think to yourself: "I wish she wasn't here." -This is what happens when you attach your identity and sense of worth to the amount of male attention you receive.
Female castration results in concentration of her feelings upon her male companion, and her impotence in confrontations with her own kind. Because all her love is guided by the search for security, if not for her offspring then for her crippled and fearful self, she cannot expect to find it in her own kind, whom she knows to be weak and unsuitable.
We can say the brotherhood of man, and pretend that we include the sisterhood of women, but we know that we don't. Folklore has it that women only congregate to bitch an absent member of their group, and continue to do so because they are to well aware of the consequences if they stay away. It's meant to be a joke, but like jokes about mothers-in-law it is founded in bitter truth.