Difference between Custom Data and Collected Data...
Collected Data : is rule which can be configured in webconsole where agent collects the data at periodic interval and upload that collected data at device check-in. This information you see in collected data tab, like Battery %age, App in foreground, WIFI SSID, IP address etc.
Custom Data: is value read from either .ini, .xml or registry presented on device. This value can be collected and show up in device details. more info about custom data is