List
list1.AddRange(new int[] { 4, 5, 6, 7, 3, 8 });
List
list2.AddRange(new int[] { 14,15, 16, 17, 13, 18 });
List
var vs = list1.Select((i, index) => new { num = i - list2[index] });
foreach (var v in vs)
list3.Add(v.num);