Is “page_cache” the same thing as full page cache in app/etc/env.php?

I was reading this article where the author shows how to configure both varnish and redis for Magento 2. In the first portion, he configured Varnish. In the second section, he ends up using this configuration to setup redis:

'cache' => 
  array (
    'frontend' => 
    array (
      'default' => 
      array (
        'backend' => 'Cm_Cache_Backend_Redis',
        'backend_options' => 
        array (
          'server' => '127.0.0.1', 
          'port' => '6379',
          'persistent' => '',
          'database' => '0',
          'force_standalone' => '0',
          'connect_retries' => '1',
          'read_timeout' => '10',
          'automatic_cleaning_factor' => '0',
          'compress_data' => '1',
          'compress_tags' => '1',
          'compress_threshold' => '20480',
          'compression_lib' => 'gzip',
        ),
      ),
      'page_cache' => 
      array (
        'backend' => 'Cm_Cache_Backend_Redis',
        'backend_options' => 
        array (
          'server' => '127.0.0.1',
          'port' => '6379',
          'persistent' => '',
          'database' => '1',
          'force_standalone' => '0',
          'connect_retries' => '1',
          'read_timeout' => '10',
          'automatic_cleaning_factor' => '0',
          'compress_data' => '0',
          'compress_tags' => '1',
          'compress_threshold' => '20480',
          'compression_lib' => 'gzip',
        ),
      ),
    ),
  ),

My question is, does the page_cache array in the above configuration overwrite Varnish? What is the difference here between “backend” cache, “page_cache”, and “full page cache” (set up in the backend of Magento).