Question: Why is it hotter on one part of the word and not the other?

Oliver Gordon answered on 6 Mar 2019:

The Earth is mainly heated by the sun. It’s a myth that the equator is hotter because it’s closer to the sun. Relative to how far away the sun is, it’s not really that different.

What matters more is the ANGLE of the sun. At the equator, the sun is mostly directly overhead. At the poles, it’s at a very shallow angle. Now, if you were to take a torch and shine it directly above a table, you’ll see that most of the light occupies a smaller surface area than if you turn the torch at an angle. The same amount of energy is coming out of the torch, but it’s more “concentrated” when it’s overhead. So more energy in any given space = more heat at that spot. Which for us just so happens to be at the equator!