A Larger Display
It may not be the biggest change or upgrade everyone was expecting, but the Apple Watch Series 7 is getting a larger screen than previous models. What Apple did was reduce the borders of the Apple Watch.
According to Apple, the borders on the Series 7 are 40% thinner than Series 6. Moreover, Series 7 features 20% more screen area than Series 6 and 50% more screen area than Series 3.