system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: The difference between 1080p, 1440p, 4k, etc... like is something putting out 4k but shown on a 1080p monitor gonna look the same as something being put out at 1080p on the same monitor?

I understood the number references the pixel count but what makes more pixels = a better pixel? And to my understanding, 4k takes two to tango.. like your system/movie/etc has to put out or support 4k resolution while your tv or monitor or whatever has to be 4k as well. So is there any benefit to having a 4k game on a 1080p display? Conversely, will a 1080p game look better on a 4k TV vs a 1080p tv?
gpt
A 4k image on a 1080p screen will usually look better than a 1080p image on a 1080p screen.

This is due to the 4k image having used more pixel data to preserve the original image in a less compressed manner. "Down sampling" the 4k image to 1080p means turning each set of 4 pixels in a square into 1 pixel in the resulting 1080p image. The result of this operation will produce a better picture than if the source material had been saved at 1080p to start with, this is due to image compression. When you compress an image you kind of squish the colors and shapes a bit to fit in nice neat patterns, this results in a blurrier image that is less accurate but saves greatly on data. A compressed 4k image still has far more image information than a compressed 1080p image, and as a result down sampling the compressed 4k image to 1080p will look much nicer than plain compressed 1080p.