Why are the screen resolution units of monitors and smartphones different?

Question

Android

Hello comrades, I'm making a game on libgdx, testing it on a laptop with a resolution of 1366x768, I find out that the popular resolution for android is 1920x1080, but this screen is 10 times smaller than the screen of my laptop (1920x1080 is 10 times smaller than 1366x768). And the question is - why do monitor and smartphone screens have different units of measurement, where can you read about this in detail? Please tell me, I've been looking for a week!

Answer 1

Units of measurement are exactly the same - pixels.
It's just that laptops have more pixels.
On the screens of outdoor advertising, pixels are generally the size of a fist.
Well, for the game you should not care about the pixels. The aspect ratio is important for drawing the interface. And models can be rendered on any viewport.

Answer 2

> but this screen is 10 times smaller than the screen of my laptop
If only in terms of area - if the proportions are similar, 15" is 7.43 times larger than 5.5".
Both there and here the units of measurement are pixels. Smartphones just have more pixels per inch.
Why is that?
• We look at the screen from a smaller distance.
• Smartphone APIs are young and therefore initially calculated for variable DPI. Existing programs will not be affected.
• And at the same time, because of the small screens and large fingers, a dense layout of controls is not required.
• Apparently, a desktop size HiDPI screen with no dead pixels would be prohibitively expensive.
Sometimes sizes are measured in "dialog units" and "device-independent pixels" (for example, 1px on the web is exactly what a "device-independent pixel" is, which can be 2 or 3 real pixels). But this is offtopic.