What is the most efficient pattern/algorithm to compare two lists and find the delta between those two lists?

Question

We have two lists, let\'s say students and their scores. I want to compare these two lists and find the delta between the new list and the old list, then find the least intrusi

Answer 1

Can you use Linq:

List list1 = GetYourList1();
List list2 = GetYourList2();
var diff = list1.Except(list2);

Your example specific:

var diff = newList.Except(existingList);

Not sure if it is the most efficient but it's concise :)