CareerCup

I was asked to explain memento pattern.I explained with this example.

class Originator:ICloneable
    {
        public string a;
        public int b;
 
        public object Clone()
        {
            Originator o = new Originator();
            o.a = this.a;
            o.b = this.b;
            return o;
        }
    }
 
    class CareTaker
    {
        List<Originator> l = new List<Originator>();
 
        public void SaveMemento(Originator o)
        {
             l.Add((Originator)o.Clone());
        }
 
        public Originator RetrieveMemento(int i)
        {
            return l[i];
        }
    }
 
    class Program
    {
        static void Main(string[] args)
        {
            CareTaker c = new CareTaker();
            Originator o = new Originator();
            c.SaveMemento(o);
 
        }   
    }

The interviewer said this is is different from memto pattern ... can anyone explain where the difference is!!!