It gets rather complicated when trying to describe the differences between Broadcast systems and Video systems so let stick to those video systems found in VCRs, camcorders, DVD and Blu-Ray Disc players etc.
Those are the basic standards and none are compatible with each other. Sometimes the A/C Hertz are 50 MHz (220 volt countries) and sometimes 60Mhz (110 volt countries) and this changes the scanning results of an electron tube, LVD or Plasma etc. 60Mhz, used in the USA for example, renders the image smoother, virtually no discernible flicker. With line doubling and quad-doubling (100 and 220 MHz and then 200 and 440 MHz).
Line doubling actually interlaces the picture into a single scan that reveals the entire frame and doubling again increased the scan lines providing for an even finer resolution and there a better sense of reality to the human eye. Technically it takes the original two-field frame and creates a progressive scan (single non-interlaced frame) output. This produces a higher resolution picture both brighter and smoother.
Some 3rd party Line-quadruplers can upscale to resolutions: 1365×1024, 720P, 1080i 852×480, 1024×1024, 1024×768 and 1365×768 and even higher. When the newest technology in video images hits the world we will be seeing NHK images of more than 6000 lines, up from the maximum of 1080P today.
If they then begin to Line-quadruple an image like that who knows what the mind might achieve if plugged directly into the motherboard of the future. Perhaps an enlarging and enhancing of human vision will be needed in the order of 1,000 eyes, 360 degree views both laterally and longitudinally, 100,000,000 lines of resolution all far outpacing current human ability.