Yes, apps can be both installed and updated on devices without prompting device users, though the required conditions for each action are slightly different.
Installing Apps "Silently"
We have written an in-depth article explaining silent app push on our blog. Here is the link:
Updating Apps "Silently"
Any managed app can be updated on a device without prompting the user. A device does not need to be supervised for the update to occur "silently".
iOS will prompt the user if the app being updated is currently open. This prompt occurs so that the app does not quit on the user while they are using it.
In the case of updating an app while the device is in single app lock (also referred to as single app mode and guided access), please see the following article for a suggested methodology:
How can I update an enterprise iOS app while in Single App lock mode?
