The 'Industrial Internet' falls unequivocally under the umbrella of the 'Internet of Things (IoT)'.
The IoT is a reference to the internetworking of "smart" or "connected" devices (physical devices, vehicles, buildings etc.) which feature electronics, software, sensors, actuators and network connectivity for the purpose of collecting and exchanging data.
Similarly, the 'Industrial Internet' refers to the integration of complex physical machinery with networked sensors and software.
Putting the two definitions next to each other makes for an easy comparison. Physical machinery (AKA 'physical devices') are now being integrated with networked sensors (AKA 'network connectivity') and software giving rise to the term 'Industrial Internet' coined by GE.
I may as well have explained the difference between apples and an apple tree...
Bill Schmarzo, author of Big Data: Understanding How Data Powers Big Business, wrote about the difference between the Internet of Things and the Industrial Internet