Since I assume the class instances for the items that are considered "the same" are different in both lists you need a custom IEqualityComparer.
Since your class doesn't implement IEquatable, you'll need to use the overload of Intersect which allows for an IEqualityComparer.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.