Yes - for example, a Medium women's road bike will be smaller than a Medium men's road bike. However, the sizing itself is calculated in the same way, so a 54cm men's and women's bike have the same frame size. Some manufacturers also change other aspects of frame geometry on a women-specific bike, to offer women a better fit. For example, women tend to have shorter upper bodies than men, so women's bikes can have shorter top tubes (the horizontal or sloping tube running between the handlebars and the saddle), to reduce the reach to the handlebars.