What exactly is "Overridden", "Needs review" & "Revert component" in Features?
Both needs review and overridden statuses mean that the feature in the database does not match the feature in code. Running "drush fr" (feature revert) will replace the feature in the database with the feature in code.

Now lets see "Revert" vs "Update"

Revert:(drush fr)

This operation changes your site configuration (living in the database) to match up with the definitions in the feature module code.

Update / Recreate:(drush fu)

The update operation will produce a modified version of your feature module, which matches up with the configuration found in the database.


  Remember, revert for Drupal features means copy configuration from
  code into the database.


If you want to go in detail with simple explanation, then please follow below links


Modifying, updating and reverting Features
Revert and update a Drupal feature module