In the JBPM 6 user guide (http://docs.jboss.org/jbpm/v6.0/userguide/jBPMBPMN2.html), The Converging AND gateway will wait until all incoming branches are completed before continuing and the Converging OR gateway will continue as soon as all direct active paths of its incoming branches has been completed.
What's the meaning and context of "direct active paths" described in the OR type gateway and its difference with "incoming branches" in the AND type gateway?
The difference is that, for an AND gateway, there is an assumption that all incoming paths will have been triggered, so you have to wait until each of them is done.
With an OR gateway, possibly not all incoming paths will be triggered, so you only have to wait for the ones that are still active (where there's still a possibility an active part of the diagram will reach the gateway).
For a more complete and technical description, I suggest you take a look at the BPMN2 specification, or explanations on workflow patterns.