title: Project.json definition dnx451 vs .dotnet ( 4.51)
body: <p>I've some 
  In asp vnext I can define 3 Types of runtime</p>
  
  <ul>
  <li>dnxCore</li>
  <li>dnx451</li>
  <li>dotnet</li>
  </ul>
  
  <p>In Project.json it looks like this:</p>
  
  <pre><code>"frameworks": 
  {
      "dotnet": { },
      "dnx451": { },
      "dnxcore50": { }
  }^
  </code></pre>
  
  <p>and the ui shors this</p>
  
  <p><img src="https://i.stack.imgur.com/O5qhk.png" alt="enter image description here"></p>
  
  <p>I assume the following:</p>
  
  <p><strong>dnxCore</strong> is the new .net Core Framework.</p>
  
  <p><strong>dotnet</strong> is the previous runtime</p>
  
  <p><strong>dnx451:</strong>
  What is different when defining "dotnet" or "dnx451" in the project.json?  </p>
  
  <p>Shouldn't both run with the .net execution runtime?</p>
  
  <p>Also depending on which project template i choose ( vNext ClassLib or vNext Console Lib) default contains one or the other.</p>