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).

Sometimes there’s little to no difference and sometimes the men’s product is better. The 99¢ shaving cream I get from the men’s section in Target is the same as the $4 women’s shaving cream. The $4 deodorant I get for the gym smells “manly,” but it works way better than the $7 ultra-strength women’s version. My fiancée will only buy men’s socks because they’re almost always double the thickness of women’s socks. When I need basic canvas sneakers, I get a pair from the boy’s section (feet are too small for men’s) because they’re usually made better than the women’s ones and look the same.