I am not quite sure what kind of comparison you are looking for.
The major differences between the HiveMQ MQTT Client Library and the Eclipse Paho Java Client are:
- Full MQTT 5 Support
- API flavors:
- Reactive, Async and Blocking
- Flexible switching
- Consistent and clearly separated
- Backpressure support:
- QoS 1 and 2
- QoS 0 (dropping incoming messages if necessary)
- Automatic and configurable thread management
You will find all the details on the project page, provided in the initial post.
Feel free to open a new thread in case you come across any specific questions.