Regular sunglasses cant reduce glare or enhance contrast as well as polarised lenses do
Blinding reflections can make you squint even if you are wearing sunglasses. High summer sun, driving in low winter sunshine; glass & water reflections all cause excessive glare & eyestrain.
Polarised lenses give 100% U.V. protection, reduce glare, improve contrast, reduce eyestrain allowing you to see clearly & comfortably.
The below video demonstrates the benefit of polarised lenses.