Differences between these two ways to construct instance(Reflect and new)

I have a Parent.class(User and Element can be replaced by any classes)

public abstract class Parent {
    User user;

    public void InitUser() {
        Fileds f = this.getClass().getDeclaredFields();

        for(int i=0; i<f.length; i++) {
             f[i].set(this, new Element(i));
        }
    }
}

Child.class

public class Child extends Parent {
    Element e1;
    Element e2;

    public Child(User user) {
   　   super();
        this.user = user;
    }    

    public void doSomethingUsingE1AndE2() {
         // do something by using e1 and e2, invoking user's methods.
         user.perform(e1);
         user.perform(e2);

    }
}

In my Client.class, is there any differences between the following two ways to construct and use Child?

1.

public class Client() {
      User user = new User();
      Class childClass = Class.forName("com.xxx.Child");

      Constructor con = childClass .getConstructor(User.class);
      Object o = con.newInstance(user);
      Method initMethod = child.getSuperclass().getDeclaredMethod(
                        "InitUser");
      initMethod.invoke(o);

      Method keyMethod = child.getMethod("doSomethingUsingE1AndE2");

      keyMethod.invoke(o);
}

2.

public class Client() {
      User user = new User();
      Child c = new Child(user);
      c.InitUser();
      c.doSomethingUsingE1AndE2();
}

Thanks a lot.