Msdn IEnumerable и MVC# 2013 разница в синтаксисе

public class Person
        {
            public Person(string fName, string lName)
            {
                this.firstName = fName;
                this.lastName = lName;
            }
 
            public string firstName;
            public string lastName;
        }
 
        public class People : IEnumerable
        {
            private Person[] _people;
            public People(Person[] pArray)
            {
                _people = new Person[pArray.Length];
 
                for (int i = 0; i < pArray.Length; i++)
                {
                    _people[i] = pArray[i];
                }
            }
 
            IEnumerator IEnumerable.GetEnumerator()
            {
                return (IEnumerator)GetEnumerator();
            }
 
            public PeopleEnum GetEnumerator()
            {
                return new PeopleEnum(_people);
            }
        }
 
        public class PeopleEnum : IEnumerator
        {
            public Person[] _people;
 
            // Enumerators are positioned before the first element
            // until the first MoveNext() call.
            int position = -1;
 
            public PeopleEnum(Person[] list)
            {
                _people = list;
            }
 
            public bool MoveNext()
            {
                position++;
                return (position < _people.Length);
            }
 
            public void Reset()
            {
                position = -1;
            }
 
            object IEnumerator.Current
            {
                get
                {
                    return Current;
                }
            }
 
            public Person Current
            {
                get
                {
                    try
                    {
                        return _people[position];
                    }
                    catch (IndexOutOfRangeException)
                    {
                        throw new InvalidOperationException();
                    }
                }
            }
        }
 
        class App
        {
            static void Main()
            {
                Person[] peopleArray = new Person[3]
                {
                    new Person("John", "Smith"),
                    new Person("Jim", "Johnson"),
                    new Person("Sue", "Rabon"),
                };
 
                People peopleList = new People(peopleArray);
                foreach (Person p in peopleList)
                 Console.WriteLine(p.firstName + " " + p.lastName);
 
            }
        }