All the iPhones presented yesterday were equipped with a new induction charging system using magnets in a similar way as in Apple Watch watches. The new system, which has gained a well known name - MagSafe - provides twice as fast charging. However, this is only possible with MagSafe chargers.
As described on the product page the new iPhones, in contrast to previous models, can be charged with a power of not 7.5 W but 15 W, provided that you use a dedicated MagSafe charger. In case of other inductive chargers, the power and therefore charging speed is the same as in case of older models and is 7.5 W.