Except « Linq Operators « LINQ

Except returns the elements in the first input sequence that are not present in the second:

 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        int[] seq1 = { 1, 2, 3 };
        int[] seq2 = { 3, 4, 5 };

        IEnumerable<int> difference1 = seq1.Except(seq2);
        IEnumerable<int> difference2 = seq2.Except(seq1);

        foreach (int i in difference1)
        {
            Console.WriteLine(i);
        }
        foreach (int i in difference2)
        {
            Console.WriteLine(i);
        }
    }
}