What is the difference between 4k and 8k?

I don't have much of a clue that 8k is the newest or is there one with even more resolution and how big is the difference between 4k and 8k when you watch a movie or play on it?

Twice as good resolution.

Enormously actually support very little or no native 8K resolution, but still a difference can be seen

In contrast to 4K, 8K doubles both the horizontal and the vertical number of pixels. This means that a total of four times as many pixels can be displayed - a total of 33 million - and this corresponds to a resolution of 7680 × 4320 pixels.