Slightly faster processors, usually with around 15-20% improvement over the previous model.

Larger on-board storage capacities.

Increased display brightness. Different colors and materials.

ECG readings (Series 4) A digital compass (Series 5)

International Emergency Calling (Series 5) A better heart rate sensor (Series 6)

A blood oxygen sensor (Series 6) A very slightly larger display (Series 7)

A thermometer that’s only useful for cycle tracking (Series 8)

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