What's the difference b/w GNC total lean shake and casein protein powder?

I bought the GNC total lean shake b/c the sales person told me it was more for women and people looking to lose weight versus building muscle with protein powder like Casein or whey. I am trying to decide if I bought the correct product. There are so many to choose from and I need to know what women need since we are very different from men when it comes to weight loss. HELP :)