Moto G is probably the first smartphone which can be updated from Android Kitkat version to all new Android 5.0 Lollipop version. However, only the Moto G 2nd Generation has got the Lollipop update.
Try to check for updates in Settings > About Device. If the update is available, you can do update it to Android Lollipop 5.0 OS.
If you're having any other edition, wait until it arrives for that too!
It is before any high-end smartphone like Nexus that a low budget smartphone, Moto G 2nd Gen has the greatest of all Android versions, available to download.