@giosal
>... why do we need UHD TV Box and UHD TV in order to watch Full HD channels?...
the clear and sufficient explanation was given by CorinaS 😁
>... won't Full HD TV be enough?...
NO❗
UHD (or ultra high definition): 3,840 × 2,160, or 4 times more pixels than Full HD
Full HD, known by the abbreviation FHD, offers a resolution whose images are 1920 pixels wide by 1080 pixels high. This corresponds to a total of 2.07 megapixels.
Ultra HD, known by the abbreviation UHD, offers a resolution of 3840 x 2160 pixels. This corresponds to 8.3 megapixels.
Even though the exact term is "UHD", marketing has now mixed everything up and when we talk about televisions (LCD, LED or OLED) the words 4K, UHD or 4K UHD mean exactly the same thing: a definition of 3840 x 2160 pixels with a ratio of 16/9.
In summary:
What is the difference between HD, Full HD and UHD?
- HD (high definition or 720p): 1,280 pixels per line × 720 lines;
- Full HD (1080p or 1080i): 1,920 × 1,080, or about 2 million pixels per frame.
Two very high definition formats:
- UHD (or ultra high definition): 3,840 × 2,160, or 4 times more pixels than Full HD