You can't tell from the outside, but the GH5 adds a ton of advanced video options, beefed up photo capabilities, improvements where needed and enhancements to Panasonic's already fast and accurate autofocus system.
Still bigger than Sony A7 series
The GH5's body is still larger than the full-frame A7 series, but the lenses for the latter are a lot bigger than comparable Micro Four Thirds versions. It's still smaller and lighter than a dSLR, though.
Moved the movie button
The record button has moved from the back of the camera to the top -- and the flash has moved off the camera entirely.
Wireless
Panasonic also added 5GHz Wi-Fi support and low-power Bluetooth.
Joystick
A joystick for direct manipulation of autofocus areas replaces the record button.
New viewfinder, LCD
A higher magnification (0.76x effective) OLED viewfinder and improved touchscreen grace the back of the camera.
Two slots!
The upgrade adds dual UHS-II slots, which will be essential for recording the high bit rate 4K video internally.
Connectors
In addition to a USB-C connection, the GH5 has a full-size HDMI connector. Panasonic will include a lock for it in the box.
New 12-60mm f2.8-4
Shown at Photokina 2016, the midrange all-in-one zoom will likely be available as a kit option with the FH5.
Still OIS after all these years
The new lens includes optical image stabilization, which works in conjunction with the sensor-shift stabilization in Panasonic's latest cameras. Click through for more pics of the Lumix GH5, and read my first take at the link below.
Panasonic Lumix GH5
Panasonic Lumix GH5
Panasonic Lumix GH5