title: Different Interop references on two different computers doesn't work
body: <p>When I add a reference to <strong>Microsoft.Office.Interop.Excel</strong> on my computer, Visual Studio adds this to the project file:</p>
  
  <pre><code>&lt;COMReference Include="Excel"&gt;
    &lt;Guid&gt;{00020813-0000-0000-C000-000000000046}&lt;/Guid&gt;
    &lt;VersionMajor&gt;1&lt;/VersionMajor&gt;
    &lt;VersionMinor&gt;5&lt;/VersionMinor&gt;
    &lt;Lcid&gt;0&lt;/Lcid&gt;
    &lt;WrapperTool&gt;primary&lt;/WrapperTool&gt;
    &lt;Isolated&gt;False&lt;/Isolated&gt;
  &lt;/COMReference&gt;
  </code></pre>
  
  <p>There is another developer on the team who gets errors and needs to add a DLL file to the project called Interop.Excel.dll, which replaces the code above with this in the project file:</p>
  
  <pre><code>&lt;Reference Include="Interop.Excel, Version=1.5.0.0, Culture=neutral, processorArchitecture=MSIL"&gt;
    &lt;SpecificVersion&gt;False&lt;/SpecificVersion&gt;
    &lt;HintPath&gt;My Project\Interop.Excel.dll&lt;/HintPath&gt;
  &lt;/Reference&gt;
  </code></pre>
  
  <p>This does work on my computer.</p>
  
  <p>Could you please explain the differences between the two methods, which is best, and how to get the first one working on other computers?</p>