Java의 변수 숨기기는 함수 재정의와 어떻게 다릅니까?

public class A {
    public int intVal = 1;
    public void identifyClass() { System.out.println("I am class A"); }
}

public class B extends A {
    public int intVal = 2;
    public void identifyClass() { System.out.println("I am class B"); }
}

public class MainClass {
    public static void main(String[] args) {
        A a = new A();
        B b = new B();
        A aRef;
        aRef = a;
        System.out.println(aRef.intVal);
        aRef.identifyClass();
        aRef = b;
        System.out.println(aRef.intVal);
        aRef.identifyClass();
    }
}

1
I am class A
1
I am class B

aRef = b;
System.out.println(aRef.intVal); // Outputs 1, the value of A's intVal
System.out.println(((A)aRef).intVal); // Outputs 2, the value of B's intVal