Women tend to have longer legs, shorter torsos and arms with narrow shoulders and small hands. Their seats are also tuned for them as well. We've fit women on WSD frames who have been riding a mans frame and most of them have stated there being a difference. With that said we haven't had too many problems fitting women on mens bikes either. Especially if they are giants by lady standards. Just takes a bit of adjusting with shorter stems, wider seats, and narrower bar. We've seen too many women stretched out on oversize male bikes with poor fittings. With all that said I have noticed a bit of trend in some manufacturers to take a lot of performance out of female bikes by using poorer components than the male specific equivalent. We have switched components on a couple of bikes for this reason. Manufacturers are getting better about this as they take note of complaints.