I've tried both, but have found the protection from P20 lasts longer. I'm a scubadiver (warm water only, so always somewhere hot and sunny) and even after a dive in a full wetsuit, the P20 goes on working for the rest of the day. Brilliant because I burn easily. Obviously you need to follow the instructions and be careful during the hottest part of the day and the length of time you stay out for the first few days, but I think that goes for all sun protection products.