OEM was "optimized" or whatever for the vehicle they are on from the factory. They were chosen or designed around it for an even balance between cost, dependability and performance.
Aftermarket has options. Material options. Type of performance. But there are a lot of factors as they are all different. It'll be materials and wear. From what I've always known, mostly performance aftermarket pads are for sports cars. For the optimal stopping power, the brake pads have to get to the proper temperature. Different materials will offer more grip when getting to those temperatures. Depending on the material, they can produce more dust/less dust or faster wear on the rotors. You might never reach the correct temperatures for the benefits. There are always trade offs and price differences. Example brakes that don't produce dust might be good to stay clean and may not wear rotors as fast as OEM, but you might lose stopping power. There could be brakes, that have better stopping power, dustless and better than OEM at every aspect, but might just be 5 times more than OEM. They're all just trade offs or they just slap the name on their for marketing. Like towing could be something that will last longer but also stop faster the hotter they get compared to OEM. Sometimes they could be better all around and you'd get more value by paying a little more. An overall upgrade from OEM. The manufacturer just didn't want to so they could keep costs lower.
Could also come down to a personal preference. Some people like mushy brakes. Some like those sharp and sensitive brakes. Could just be all about details or brand loyalty.
Aftermarket has options. Material options. Type of performance. But there are a lot of factors as they are all different. It'll be materials and wear. From what I've always known, mostly performance aftermarket pads are for sports cars. For the optimal stopping power, the brake pads have to get to the proper temperature. Different materials will offer more grip when getting to those temperatures. Depending on the material, they can produce more dust/less dust or faster wear on the rotors. You might never reach the correct temperatures for the benefits. There are always trade offs and price differences. Example brakes that don't produce dust might be good to stay clean and may not wear rotors as fast as OEM, but you might lose stopping power. There could be brakes, that have better stopping power, dustless and better than OEM at every aspect, but might just be 5 times more than OEM. They're all just trade offs or they just slap the name on their for marketing. Like towing could be something that will last longer but also stop faster the hotter they get compared to OEM. Sometimes they could be better all around and you'd get more value by paying a little more. An overall upgrade from OEM. The manufacturer just didn't want to so they could keep costs lower.
Could also come down to a personal preference. Some people like mushy brakes. Some like those sharp and sensitive brakes. Could just be all about details or brand loyalty.