Why are Figma frames weird?

Question

Design

Figma has built-in templates for different devices that can be used as a Frame. But why are there such strange permissions? For example, for iPhone 8 375x667. While the actual resolution is much higher. Or the same HD there 1440x1024, but what kind of HD is it ??? I don't understand the logic.

Answer 1

First we smoke this:
https://material.io/guidelines/layout/units-measur...
Then this:
https://material.io/devices/
The first link to smoke for a long time and carefully, since there is no basic knowledge.