title: Get the difference between two lists using LINQ
body: <p>I have two lists and I need to compare them and only return a List of Items not in both.</p>
  
  <pre><code>var listOfIds = new List&lt;int&gt; {1,2,4};
  
  var persons = new ObservableCollection&lt;Person&gt;
  {
      new Person {Id = 1, Name = "Person 1"},
      new Person {Id = 2, Name = "Person 2"},
      new Person {Id = 3, Name = "Person 3"},
      new Person {Id = 4, Name = "Person 4"}
  };
  </code></pre>
  
  <p>In this example <code>new Person {Id = 3, Name = "Person 3"}</code> would be the result.
  A Linq solution would be preferred.</p>