Ubuntu 16.04 LTS
, codenamed Xenial Xerus, will be the 6th iteration of the world’s most popular Linux distribution. The release date of Ubuntu 16.04 LTS is set for April 21, 2016.Xenial Xerus will receive ongoing security and critical bug fixes until 2021. With this release, Canonical is making some key changes to the OS.

Let’s have a look in to important changes

Online search in Unity’s dash is disabled 
In the current versions of Ubuntu, a wide range of non-identifiable data is sent to Canonical, which is used to provide you contextual results from multiple online services. While anyone can turn off this online search from Ubuntu System Settings, the open source community hasn’t been a great fan of this feature.
Well, if you think you are going to miss this online search functionality, you can enable it in Ubuntu 16.04 LTS, the same way you disable it in the current versions. Just go to Ubuntu System Settings > Privacy > Search and Turn the slider ‘On’.

Ubuntu Software Centre is no more
Users of the Xenial Xerus desktop will find that the familiar  Ubuntu Software Centre is no longer available.GNOME’s Software application will – according to current plans – take its place as the default and package management utility on the Unity 7-based desktop.

Alpha 1 in the Ubuntu 16.04 ‘Xenial Xerus’ development cycle is now available to download.
For Lubuntu 16.04 Alpha 1

Click here
For Ubuntu MATE 16.04 Alpha 1
Note : Alpha releases are NOT intended for use in “production environments”; e.g., your main laptop, your work PC, etc.