title: Julia: Difference between Type and DataType
body: <p>To me they seem to be the same. Since <code>Type</code> is of type <code>DataType</code> and vice-versa, how are they not equivalent? When should I use one versus the other?</p>
  
  <pre><code>&gt; isa(DataType, Type)
  true
  
  &gt; typeof(Type)
  DataType
  
  &gt; isa(Type, DataType)
  true
  
  &gt; typeof(DataType)
  DataType
  </code></pre>