"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AirPods and AirPower: Everything We Know
Apple Watch Series 4 Teardown: 20% Less Battery Capacity, Hidden Barometric Sensor, and Streamlined Internals [Updated]
The repair experts believe that while the original Apple Watch was awkwardly layered together and used too much glue, the Series 4 lineup feels "much more thoughtfully laid out," likening it to the iPhone 5.
Apple pundit John Gruber has compared this to the leap in design brought by the iPhone 4, and we might even go a bit further and call it an iPhone 5: a device that knows its priorities, and wants to look as elegant inside as out.At first glance, the internal design of Series 4 models looks more or less the same as previous models, with the battery and Taptic Engine taking up most of the space. Dig deeper, however, and the changes become evident.
- 1.12Wh battery in the 44mm model, which is 20% less capacity than the 1.34Wh battery in 42mm-sized Apple Watch Series 3 models.
- A thinner and longer Taptic Engine, but iFixit says it still takes up a lot of space that could have gone to a larger battery.
- The barometric sensor may have been relocated to the speaker grille for access to the outside atmosphere. The sensor had its own dedicated hole beside the microphone on Apple Watch Series 3 models.
- The new Apple S4 chip is secured only with screws, whereas the processor is also "fiercely glued" in previous Apple Watch models.
- The golden ring is likely a streamlined antenna system, as iFixit says it has not seen the usual fiddly brackets or golden gaskets.
- The entire rear casing pops off more easily.
- The display is not only larger, but also thinner.
All in all, the Series 4 received a "solid" 6/10 on iFixit's repairability scale, with 10 being the best possible score. That's the same repairability score iFixit gave the iPhone XS and XS Max in its teardown of those devices.
Update: A previous version of this article said Apple Watch Series 4 models have 4% more battery capacity, as iFixit mentioned, but that was based on comparing a 44mm Series 4 model with a 38mm Series 3 model. 44mm and 40mm Series 4 models actually have 20% less battery capacity compared to 42mm and 38mm Series 3 models respectively, although Apple says battery life remains up to 18 hours.