Start off with this tweet:
There is a reason Apple didn’t talk about the Apple Watch Series 7 CPU this year…
— Steve Troughton-Smith (@stroughtonsmith) September 15, 2021
…and it’s because it’s the exact same as last year’s Series 6 👀 In fact it doesn’t even get a new model number, it’s effectively just a chassis tweak pic.twitter.com/mLsTNkdTNO
This prompted a lot of speculation about just how much changed from the Series 6 to the Series 7.
From the headline linked post from Sami Fathi, MacRumors:
As noted by Steve Troughton-Smith, the CPU in the S7 chip carries the same t8301 identifier as the CPU in the previous S6 chip, which explains why Apple’s performance claims are unchanged relative to the S6.
Much is the same, the primary difference being the slightly larger screen, which would explain the slightly heavier weights of the various Series 7 models.
Also:
With the Apple Watch Series 7, Apple includes faster charging, claiming that it can charge to 80% in just 45 minutes and that 8 minutes of fast charging will provide sufficient battery life for 8 hours of sleep tracking. To support the new fast charging, Apple will be offering a new 1-meter USB-C magnetic fast charging cable.
And:
On the connectivity front, the Series 7 includes the same Bluetooth 5.0 protocol as the Series 6, but, unlike the Series 6, the new Apple Watch Series 7 also has built-in support for Beidou, China’s satellite navigation system.
The fast charging strikes me as the biggest improvement, which will make charging after a night of sleep monitoring much more practical.
And the satellite nav support in China (and there’s a U1 chip too) is an interesting wrinkle.