Question: I do not know the difference between a pipe queue and batch queue.
Answer: Batch queues execute jobs directly on the computer on which they reside. Pipe queues route jobs from the computer where they exist to other pipe or batch queues.
Question: I do not know when to use a pipe queue.
Answer: A good time to use pipe queues is when you want to use any of several execution locations, any of which may or may not be available. You can configure a pipe queue to have multiple destinations (pipe or batch queues to route to). When a job is submitted to the pipe queue, it will be routed to the first available destination.