Watch Series 4 40mm vs Watch Ultra 49mm

The Apple Watch Series 4 feature set includes a Retina display with a max brightness of 1000 nits, S4 SiP with a 64-bit dual-core processor, a W3 wireless chip, a second-generation optical heart sensor, water resistance to 50 meters, a barometric altimeter, Bluetooth 5.0, a built-in speaker and microphone, and 16GB of storage space.

In comparison, the Apple Watch Ultra feature set includes an always-on Retina display with a max brightness of 2000 nits, a flat sapphire crystal display, an S8 SiP with a 64-bit dual-core processor, a W3 wireless chip, a U1 ultra wideband chip, an Action button, a temperature sensor, a blood oxygen sensor, a third-generation optical heart sensor, International Emergency calling, Crash Detection, a water temperature sensor, a depth gauge, water resistance to 100 meters, an IP6X rating for dust resistance, a Compass, an always-on altimeter, Bluetooth 5.3, dual speakers and a three-mic array with beamforming, fast-charging, 32GB of storage space, and a new Wayfinder watch face.

The Apple Watch Series 4 and the Apple Watch Series 8 both feature a Digital Crown with haptic feedback, an electrical heart sensor, high and low heart rate notifications, irregular rhythm notification, an ECG app, Emergency SOS, Fall Detection, GPS/GNSS, and WiFi (802.11b/g/n).