1. App permissions
Now you can choose to accept or deny individual permissions as you see fit. You can deny any permission and still continue to use the app.
2. Fingerprint support
Fingerprint sensors to unlock your device, make purchases in Google Play, authenticate transactions in apps, and pay in stores. But your device will need a hardware fingerprint scanner for this.
3. Battery and Charging
When your device is at rest, the new function called Doze automatically puts it into a sleep state to increase your standby battery life.
USB Type C support, which provides faster charging
4. Improved Text selection actions
Small but meaningful change in Marshmallow is it handles copy and pasting text.
Smarter text selection, built-in undo/redo, and text actions closer to your fingers.
5. Chrome Custom Tabs
Chrome Custom Tabs will allow apps to open a customized Chrome window on top of the active app, instead of launching the Chrome app separately.Marshmallow will allow apps to pre load certain web content before sending you over to an in-app Chrome tab.