Most people who buy sunglasses primarily decide based on the frame, but it's even more important to choose the right lenses in the frame based on the specific area of use the sunglasses is intended for.
The big difference between filter sunglasses and sunglasses is that filter sunglasses absorbs unwanted light and sunglasses absorbs parts of all light. You can compare it with hearing protection that only reduces the noise while letting all useful sound through (filter sunglasses) and a normal hearing protection that reduces all kind of sounds (sunglasses). You can also customize filter sunglasses and determine what kind of light is considered as noise. This is extremely important and what we perceive as annoying light is individual.
In short, filter sunglasses gives better protection, better contrast and more comfortable vision than normal sunglasses.