title: How merge two lists of different objects?
body: <p>Using C# with LINQ, how can I merge two lists of <em>different</em> objects, say, Seminar and Conference?
  They have some common and some different fields/properties and do not share unique id. </p>
  
  <pre><code>class Seminar
  {
     int id,
     DateTime joinDate,
     string name
  }
  
  class Conference
  {
     Guid confNumber,
     DateTime joinDate
     Type type
  }
  </code></pre>
  
  <p>I have a list of:</p>
  
  <pre><code>List&lt;Seminar&gt;
  List&lt;Conference&gt;
  </code></pre>
  
  <p>I need to merge them into a super <code>List</code>:</p>
  
  <pre><code>List&lt;Object&gt;
  </code></pre>
  
  <p>A code snippet would be great help.</p>