Why do women "hate" on other women?

All women have a beauty that cannot be matched by a man in any way. A woman's body is a work of art, and therefore we should embrace our curves and our soft skin. Women have a bond with each other that cannot be broken. You all know about the code I am referring to: when a girl tries to take your man, she is labeled a homewrecker and socially ostricized from the "clique". That is why we would, hopefully never, have sex with our best friend's man, or our sister's husband. Unlike the opposite sex, who are actually surprised that girls even have a code. Men don't seem to care so much about this "code" amongst themselves. Because we have this bond, it leads me to wonder why there is so much hatred between some women? It's happened to the best of us: You are at the mall and pleasantly shopping in your cute bordello heels and a matching cheetah print purse, when you see another woman pass you, so you greet her with a friendly smile. Yet, it is met with a head-to-toe disgusted look, instantly wiping the smile off your face. As a young girl I thought this meant that there was something wrong with me, or my outfit, and would instantly look down to see if there is something going on I don't know about. On the contrary, it actually means quite the opposite. A woman will react that way to you because, subconsciously, she thinks you are very beautiful. She actually likes what she sees. Maybe it is pride that won't allow her to just say, "I like your shoes", but I assume that it stems from some insecurity that she has. The need to "hate" on another woman because you feel she looks better than you could simply vanish if we all start to respect and admire the beauty in each other. Which is why I believe that if women would work on their self-confidence and limit the amount of insecurities they have, this interchange of expressions between girls wouldn't occur, thus making life a little more positive. Which is what we all strive for anyway, right?