Declaring an array reserves enough space to hold all the elements of the array.
It also creates a symbol table entry for the array's name.  That entry 
indicates the address of the array.  So, for many uses, the array name
can be thought of as a pointer.  Unlike a pointer, though:

- there is no space allocated to hold the pointer value associated
  with the array name, and so
- you cannot assign a new value to the array name

In the example, the declaration of array causes 40 bytes to be reserved.
The declaration of p causes 8 bytes to be reserved. So, while you can
apply the indexing operation to any pointer (e..g, p[3]), allocating
a pointer does to allocate space for an array -- only for a pointer.