Controllers and devices serve very different purposes in an Avi-on network.
Controllers are switches or sensors that tell other things to change state, like turning on and off.
Devices are things like lights that are turned on and off by controllers.
The Remote Access Bridge (RAB) converts bluetooth signals from devices and controllers to wi-fi signals accessible by a wi-fi router, there by acting as a BRIDGE between the Avi-on network and the Avi-on cloud.
Mobile handsets (iOS or Android phones and tablets) are a multi-purpose mechanism for programming and operating the network.
The Avi-on Cloud is a multi-purpose utility. Here are just a few.