What is the difference between IoT and IIoT?

The big difference between the Internet of Things (IoT) and Industrial Internet of Things (IIoT) is their general usages. IoT is most commonly used for consumer usage, whereas IIoT is used for industrial purposes, such as manufacturing, plant floor monitoring, etc. 

Here is a great overview from HECO's Helpful Articles resource:

• What are IIoT Motors?