title: What is the difference between a layer with a linear activation and a layer without activation?
body: <p>I'm playing with Keras a little bit and I'm thinking about what is the difference between linear activation layer and no activation layer at all? Doesn't it have the same behavior? If so, what's the point of linear activation then?</p>
  
  <p>I mean the difference between these two code snippets:</p>
  
  <pre><code> model.add(Dense(1500))
   model.add(Activation('linear'))
   model.add(Dense(1500))
  </code></pre>
  
  <p>and</p>
  
  <pre><code> model.add(Dense(1500))
   model.add(Dense(1500))
  </code></pre>