In C are arrays pointers or used as pointers

Question

First, look at this code

When this is run, it gives the below result

(The pointers are 8 bytes long because I am running 64 bit architecture)

From my knowledge, I always thought that arrays are simple pointers to a sequence of values stored in memory and when declare some array, you are creating a pointer and allocating space for the sequence it is pointing to.

In my code, if "y" is the constant pointer, why do it got size of 20?Is the variable y replaced by memory address during compilation time or what happens? Anyone knows about this much better?