Apart from size, the other main difference between men's and women's sunglasses is obviously the design. In general, women's sunglasses tend to have more rounded shapes, curvier designs, and feminine touches. Glamorous oversized lenses and wider arms are also popular.
High-tech polarized lenses reduce glare from reflective surfaces such as water and snow to improve definition and reduce eye fatigue. Even more advanced photochromic lenses change tint in response to changing light conditions, so your sunglasses are always just as dark as you need them to be.
Some sunglasses have interchangeable lenses, meaning you can replace lenses for those of a different tint when lighting conditions change, when you've damaged a lens, or when you feel like switching up your look a little. Most styles come with a second set of lenses to give you a couple of options right out of the box.