title: Difference between two lists with linq
body: <p>I have two lists with two fields. I don't know before hand which one is larger.</p>
  
  <p>I want to achieve this:</p>
  
  <pre><code>        newList              oldList
  Fruit       Qty     Diff    Fruit       Qty
  --------------------------------------------
  apple       3       +1      apple       2
                      -2      pear        2
  peach       4       +3      peach       1
  melon       5        0      melon       5
  coconut     2       +2      
  mango       4        0      mango       4
  banana      2       -1      banana      3
  lychi       1       +1      
                      -3      pineapple   3
  </code></pre>
  
  <p>One the left you can see newList on the right the oldList. If I compare oldList against newList I want to see every possible row and difference in Quantity between the two lists.</p>
  
  <p>I wrote this, which would give me Fruit that's not contained in both lists (xor)</p>
  
  <pre><code>var difference = newList.Select(x =&gt; x.Fruit)
                          .Except(oldList.Select(x =&gt; x.Fruit))
                          .ToList()
                          .Union(oldList.Select(x =&gt; x.Fruit)
                          .Except(newList.Select(x =&gt; x.Fruit))
                          .ToList());
  </code></pre>
  
  <p>But I'm lost on how to combine it with Qty as well.</p>