Android 5.1 lollipop is slated to push in the first quarter of next year (Jan-Mar) to Nexus devices, GPE devices, and more likely Moto devices. Below is the list of improvements.
- Silent mode added after missing on Android 5.0
- General improvements in system stability
- Improved RAM management
- Fixes for sudden app closures
- Improved battery management
- Excessive consumption of network devices when used Wi-Fi fixed
- Issues with wireless connections fixed
- Problems with Okay Google function solved
- Notifications problems solved
- Some sound problems experience by certain devices fixed
- Other improvements and changes
- Changes in the Material Design color palette (after users complaints, possibly for a higher version though)
Thanks: @ggrant3876
Source: Exclusive Android 5.1 release date and improvements revealed - AndroidPIT