Windows 10: What to expect in the consumer preview

Continuum
Continuum dynamic user interface enabled

Desktop
Dropdown lists have been given a revamp
There are new animations for maximize and restore
Cortana is enabled by default
The taskbar has a new design
The search button is now a search bar by default
New backgrounds

Media support
System-wide support for the FLAC audio format

WinRT
The settings Charm has been removed
Settings fly-out now appears within an app
The title bar has been revamped, full screen is now on the bar instead of in an option menu
A lot of apps dropped the "Permissions" tab (when it's empty)
Apps can be installed on an SD

Internet Explorer
Improved support for ECMAScript 6
Improved support for ECMAScript non-standard

Apps
Settings has been revamped with a new interface
Multiple new settings have been added
Multiple other panels have been improved with more functionality, like Battery saver, Storage Sense, and more
Windows Update has been extended with a lot of new functionalities to replace the Control Panel counterpart
Calculator has been revamped
Alarms has been revamped
There is now a world clock function
Xbox has been revamped
Get started has been revamped
Photos has been added as an app (not to confuse with Photos)
Store beta has been added as an app (not to confuse with Store)
Maps has been revamped
Windows Feedback has been revamped
Sound recorder has been revamped
Lumia Camera Beta has been added as an app
Xbox has been added as an app (not to be confused with Games)

And further
The Windows kernel has been updated from version 6.4 to 10.0
 
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