I have downloaded Android N Dev Preview 3 in my Nexus 6P to explore the features and new updates of Android N. After research I found new visual changes in Android N Dev Preview 3. They made visual changes in battery notification drop down option. New Drop down version will let you access battery saver option quickly.
These kind of changes, you can simply identify. They have removed battery icon from the top of the notification drop down menu. They also made some design changes in battery saver mode. When you enter into the battery saver mode, you will not see an duplicate battery icon in the top left and you also not see non-dismiss-able notification icon.
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They also made battery saver mode easily accessible. Now you don't need to go into Settings»Battery section to enable battery saver mode. They have added it under the overflow menu. You can easily turn it on and OFF from overflow menu.
You don't have to install Android N Dev Preview 3 to get these feature they also added this feature in older version.