Difference set
List<string> list = new List<string>() { "1111", "22222", "3333", }; List<string> list2 = new List<string>() { "1", "2", "3", "1111" , }; List < String > numbers2 = Enumerable.Except (List, List2) .ToList (); // return the difference between the data set returned to 22222,3333 first main