4K resolution
As noted above, DCI 4K is 40962160, while 4K UHD is 38402160, producing a slight difference in aspect ratio rather than a significant difference in resolution. Traditional displays, such as LCD or OLED, are 3840 pixels across the screen, with each pixel being 1/3840th of the screen width. They do not overlap—if they did, they would suffer reduced detail. The diameter of each pixel is basically 1/3840th of the screen width or 1/2160th of the screen height - either gives the same size pixel. That 38402160 works out to 8.3 megapixels, the official resolution of 4K UHD (and therefore Blu-ray UHD discs).
Phantom (UAV)
The 4K was released in early 2016. Although both the controller and the aircraft appear to look similar to the Phantom 3 Advanced/Professional, the system is very much like the Phantom 3 Standard in that it uses 5.8 ghz for control and uses a 2.4 ghz wifi signal for FPV and telemetery. The range is slightly improved. The controller lacks hdmi / usb ports. The aircraft includes the Visual Positioning System module seen on the Professional/Advanced models.