There really isn't a difference, and when there is, the price difference doesn't make sense. Let's look at razors. I find that not only are men's razors cheaper but they also cut closer to the skin without damaging it. I never buy female razors because of the price and limited range/ability to shave. Men's underwear is also usually cheaper too, made of softer material than most women's underwear, and more comfortable even when there is a women's equivalent (boyshorts are usually shorter than men's trunks which cover a lot more and are more flexible).