The process invoked by the Subflow activity is called subprocess. You can use any process as a subprocess.
Simplify a process.You can group related activities in a subprocess and then invoke the subprocess from a Subflow activity. The Subflow activity represents a high level task.
Reuse processes. You can invoke a process from multiple Subflow activities defined in different processes.
Enable Business-to-Business (B2B) communication between processes. A Subflow activity can invoke a process that is running in another Engine that might belong to another company.
Distribute work load across multiple Process Executions Engines. You can distribute the work load of your process by adding Subflow activities that invoke processes that are running in another Process Execution Engine.