The Android system is developed by Google and so is the latest Nexus 9 tablet. This is why it is surprising to see the Nexus 9 still pending to receive the Android 5.1 update when on the other hand, the OS is already being rolled out to the old Motorola Moto G.
Of course, this is for the Google Play Edition of the device but it does sound bizarre to see a Nexus coming behind a non-Nexus smartphone in terms of receiving an OS update.
In detail, the Android 5.1 is now available for the Moto G and it carries the build number LMY47M. Sized at about 171MB, the Android 5.1 was rolled out OTA.
SO if you are using the Google Play Edition of the Moto G , then you should have received the update prompt by now. If not, then you can head over to the Software Update page listed in the device’s settings to manually search for the Android 5.1 update.