title: Django CharField blank vs default empty
body: <p>What is the difference between this two fields in a Django app? What behaviour should I expect?</p>
  
  <pre><code>field_a = CharField(max_length=50, verbose_name='field_a', blank=True)
  field_b = CharField(max_length=50, verbose_name='field_b', blank=True, default='')
  </code></pre>