Diff two lists

public static class ListHelper
{
public static List<t> GetUpdatedList<t>(this List<t> oldList,
List<t> newList) where T : class
{
List<t> itemsToAdd = new List<t>();
List<t> itemsToRemove = new List<t>(oldList);
foreach (var item in newList)
{
if (oldList.Exists(t=&gt;t==item))
{
itemsToRemove.Remove(item);
}
else
{
itemsToAdd.Add(item);
}
}
return itemsToAdd.Concat(itemsToRemove).ToList();
}
}