title: Get difference of arrays in Ruby
body: <blockquote>
  <p><strong>Possible Duplicate:</strong><br />
  <a href="https://stackoverflow.com/questions/80091/diff-a-ruby-string-or-array">diff a ruby string or array</a></p>
  </blockquote>
  
  <p>I have an old array: <code>[1, 2, 3, 4, 5]</code>, and new: <code>[1, 2, 4, 6]</code></p>
  <p>How to get difference with Ruby: that <code>5, 3</code> was removed and <code>6</code> was added?</p>