the formulation is slightly different. Yasmin has 30 mcg of estrogen per active pill, Yaz has 20mcg. Yasmin is set up as a 21/7 cycle of active/placebo pills, while Yaz is 24/4. The amount and type of progesterone is the same. Both are made by the same company, but Yasmin has a generic version out called Ocella. Yaz has no generic.