Under the hood, there have been updates to many core packages, including a new 4.8-based kernel, a switch to gcc-6, and much more.
Ubuntu Desktop has seen incremental improvements, with newer versions of GTK and Qt, updates to major packages like Firefox and LibreOffice, and stability improvements to Unity.
Upgrade Ubuntu desktop from 16.10 to 16.04
Open the "Software & Updates" Setting in System Settings.
Select the 3rd Tab called "Updates".
Set the "Notify me of a new Ubuntu version" dropdown menu to "For any new version".
Press Alt+F2 and type in "update-manager" (without the quotes) into the command box.
Update Manager should open up and tell you: New distribution release ‘16.10' is available.
If not you can also use "/usr/lib/ubuntu-release-upgrader/check-new-release-gtk"
Click Upgrade and follow the on-screen instructions.
Upgrade Ubuntu server from 16.10 to 16.04
Install the update-manager-core package if it is not already installed.
Make sure the Prompt line in /etc/update-manager/release-upgrades is set to normal.
Launch the upgrade tool with the command sudo do-release-upgrade.
Follow the on-screen instructions.