1. A7R III uses the NP-FZ100 Lithium-Ion Battery from Sony a9 Finally a7RII gets a battery with LOTS of life! While results will vary among users, I’ve on many occasions been able to shoot over 4,000 frames of Raw + Jpeg on a single NP-FZ100 battery. If you need even more battery life, a7R III is compatible with Sony VG-C3EM Vertical Grip (available here) which allows you to keep two batteries locked and loaded.
2. USB 3.1 Type-C Connection for Tethering! If you tether, this may actually be Number One on your list. Sony really needed to update the USB-2 multi-terminal port used for tethering in previous Sony cameras. The multi-terminal port remains for remote triggering and in-camera battery charging, tethering has been moved to a much faster USB 3.1 Type-C Connection!
In addition, you can now choose save images BOTH to the SD card and PC for redundancy or select options like saving RAW to SD card and while sending only Jpegs to your PC for faster edit.
3. Dual SD Card Slots Another great new feature from a9 that comes over to a7RII is Dual Card Slots including a UHS-II SD card slot for best faster recording.
4. 10 FPS Continuous Shooting with Either Mechanical or Electronic Shutter While a7R III can’t match a9’s 20 FPS, it’s mechanical shutter offers the ability to shoot with flash up to 10 FPS – twice the speed of a9!
5. New Image Processor and LSI for Better Image Quality