Moto G has a quad-core Snapdragon 400 CPU and 1GB of RAM. The Moto G is also quite lightweight thanks to its modestly-sized 4.5″ 1280×720 HD display, weighing in at just 143 grams. It originally shipped with Android 4.3 Jelly Bean, but has since been upgraded to Android 4.4 KitKat, and is promised future updates directly from Google.
Android 5.1 has been recently rolled out to some of the Nexus and Android One devices. Other devices will get sooner or later. In the meantime, instead of waiting for the official update, you can update Moto G to Android 5.1 via the AOSP ROM. Follow the guide below.