ARM different array size by complier

I faced the wired situation.
I have two questions.

I declared the global variable of structure array type as below.
A_TYPE gstXXXX[16];

Then, two functions wanted to look for the address of gstXXXX[1].

Q1)
At first function, the address of gstXXX[1] was &gstXXX[0]+1464. But other funtion calculated the address of gstXXX[1] was &gstXXX[0]+1480.

Q2)
I declared three structures by the same type.
typedef struct A { }
typedef struct B { }
typedef struct C { }

But the result of sizeof them are different.
sizeof(A)=124, sizeof(B)=140, sizeof(C)=124

What happened?
I cannot understand them.

Please let me know something, if u have ever experienced this problem.