gcc compile error: cast specifies array type

The following code is perfect valid,

int *ia = (int[]){1,3,5,7};

but when I compile the next line of code,

char *p = (char[]) "abc";

gcc says

test.c:87: error: cast specifies array type

It seems they are casted in the same way. Why did the second one get an err msg?

As you guys said, "abc" is a pointer, which cannot be converted to be a pointer. So my another question: why does

 char[] s = "abc";

is valid. How does the above line of code work when compiling?