Lou spends her time modeling, designing a line for Lee Cooper, and just generally being social and looking fabulous. Her style is bohemian, eclectic, and fun.
While I think I might like Lou's style better, I think I like Charlotte as a whole better. She is a very successful actress and singer and, unlike her American counterparts who have tried this two-in-one deal (ahem, Scarlett Johansson, ahem), she is talented at both arts (you must see Ma femme est une actrice/My wife is an actress). Her style is simpler than her half-sister's, with more of a focus on classic tailoring and menswear inspired pieces.