The most noticeable change coming to the Series 4 is the redesign of the chassis. The watch is 30-percent larger on its face (40mm and 44mm) and thinner front-to-back. Despite the physical overhaul, Apple still managed to wedge in a battery that will remain consistent with the Series 3’s 18 hours of usage on a charge.
A slightly more subtle change in the design is a repositioning of the microphone so that it is on the opposite side as the speaker.