Series 4 (GPS) Features | | Series 4 (GPS Cellular) Features |
| Silver aluminum case | | Silver aluminum case |
| Built-in GPS, GLONASS, Galileo, and QZSS | | LTE and UMTS |
| S4 with 64-bit dual-core processor | | Built-in GPS, GLONASS, Galileo, and QZSS |
| W3 Apple wireless chip | | S4 with 64-bit dual-core processor |
| Barometric altimeter | | W3 Apple wireless chip |
| Capacity 16GB1 | | Barometric altimeter |
| Optical heart sensor | | Capacity 16GB1 |
| Electrical heart sensor | | Optical heart sensor |
| Improved accelerometer up to 32 g‑forces | | Electrical heart sensor |
| Improved gyroscope | | Improved accelerometer up to 32 g‑forces |
| Ambient light sensor | | Improved gyroscope |
| LTPO OLED Retina display with Force Touch (1000 nits) | | Ambient light sensor |
| Digital Crown with haptic feedback | | LTPO OLED Retina display with Force Touch (1000 nits) |
| Louder speaker | | Digital Crown with haptic feedback |
| Ion-X strengthened glass | | Louder speaker |
| Sapphire crystal and ceramic back | | Ion-X strengthened glass |
| Wi-Fi (802.11b/g/n 2.4GHz) | | Sapphire crystal and ceramic back |
| Bluetooth 5.0 | | Wi-Fi (802.11b/g/n 2.4GHz) |
| Built-in rechargeable lithium-ion battery | | Bluetooth 5.0 |
| Up to 18 hours of battery life2 | | Built-in rechargeable lithium-ion battery |
| Water resistant 50 meters3 | | Up to 18 hours of battery life2 |
| watchOS 5 | | Water resistant 50 meters3 |
| | watchOS 5 |
