100W fast charge is much faster than 15W fast charge. The 100W fast charge can charge the device in a short time, quickly restoring the power, so you can get back to work faster. In contrast, the 15W fast charge can also be quickly charged, but the charging speed will be much slower. Therefore, if you need to charge quickly and have more time and charging needs, then 100W fast charge is the better choice.
The 100W fast charge is faster than the 15W fast charge. In general, the higher the power of the fast charge, the faster the charging speed. The power of 100W fast charge is much higher than that of 15W fast charge, so in theory, 100W fast charge should be able to fully charge the device faster. The actual charging speed will also be affected by factors such as the battery capacity of the device, the quality of the charger and the data cable.