4K 3840x2160 vs 4096x2160 ?

[Out Of Bubblegum]

I just bought a new TV for couch gaming. A Samsung Q70R 49 inch. It is supposed to support gaming:
https://www.samsung.com/us/televisions-home-theater/tvs/qled-4k-tvs/49--class-q70-qled-smart-4k-uhd-tv--2019--qn49q70rafxza/

I have an AMD 5700XT video card. In Windows it says that 3840x2160 is recommended setting. That makes sense, because that is 4K resolution. But it also says I can enable 4096x2160. This confuses me. Why? Does the panel actually have those 256 extra lines? Or is it something odd with the timing frequencies?

[mimizukari]

3840x2160 is what games will support.

[Snow]

Автор сообщения: Out Of Bubblegum

In Windows it says that 3840x2160 is recommended setting. That makes sense, because that is 4K resolution.

That's what you got wrong. 3840x2160 is not 4K, it's 4K UHD, and 4K is 4096x2160. It's been like that for a while, like back in the day DCI established 2K standard, and consumers got FHD instead.

[Out Of Bubblegum]

OK. I guess that is why the 4096 shows up in the settings. But the panel probably only has 3840 pixels. I can just ignore the 4096 setting. 1920x2 = 3840 and 1080x2 = 2160. So I am confused on why 4096 is true 4K. I guess 1920x1080 is not true 2K?

[Snow]

Автор сообщения: Out Of Bubblegum

OK. I guess that is why the 4096 shows up in the settings. But the panel probably only has 3840 pixels. I can just ignore the 4096 setting. 1920x2 = 3840 and 1080x2 = 2160. So I am confused on why 4096 is true 4K. I guess 1920x1080 is not true 2K?

You guessed it right. True 2K is 2048x1080.