What is the major difference between S & E?

The technical difference between S and E is the location of the GPS: Ticwatch S has the GPS built into the watch band for better tracking, Ticwatch E has traditional replaceable straps and GPS built into the watch body. The design difference between S and E : The Ticwatch S is 45mm in diameter and 13mm thick while weighing in at 45.5g. It also has a fixed, “breathable” watch band designed for workouts which minimizes sweating under the band. Ticwatch E is 44mm in diameter and 13.55mm thick while weighing in at 41.5g.The strap material: Ticwatch S : TPU Ticwatch E: Silicon