Notifys you to Update Whatsapp to new edition. Clicking on the message will directly get you for the store hyperlink to update the version.
Notifications is going to be shown whenever there's a new update.
Update for Whatsapp checks and updates latest version of Whatsapp from official Whatsapp website directly. You are able to install this app on your own Android tablets and smartphones.
As you may know Whatsapp publishes updates with latest features more regularly on official website than in the store. Update Whatsapp serves you possibility to control whether new versions can be found on Whatsapp official web address and update it !