title: What is the difference between two template types and two template parameter lists?
body: <p>What is the difference between these two declaractions?<br><code>template&lt;typename T, typename U&gt;</code><br><code>template&lt;typename T&gt; template&lt;typename U&gt;</code></p>
  
  <p>This was vaguely explained in the accepted answer on this question:
  <a href="https://stackoverflow.com/questions/3595859/too-many-template-parameter-lists-error-when-specializing-a-member-function">&quot;too many template-parameter-lists&quot; error when specializing a member function</a></p>
  
  <p>I understand that they are not the same thing, but I'm having trouble finding resources that teach usage of the latter. Explanation and examples would be much appreciated.</p>