What's the difference between `usize` and `u32`?

Question

The documentation says usize is

Operations and constants for pointer-sized unsigned integers.

In most cases, I can

Answer 1

Adding to @Levans' answer,

The size of usize is depended on how much size it takes to reference any location in memory.

on a 32 bit target usize is 4 bytes and on a 64 bit target usize is 8 bytes