A Pipeline is a workflow or a set of workflows designed to run a specific process.
A CommandSet is an XML element that contains the instructions to execute different jobs in a pipline. A CommandSet may contain one or more CommandsSets or Commands. The attribute 'type' of a CommandSet indicates the mode (serial / parallel ) to process all the Commands / CommandSets within the same CommandSet.
A Command is an XML element that contains the instructions to execute a single job.
A WorkFlow instance is an XML file that contains a CommandSet with all the necessary information / instructions to execute a specific Pipeline. The WorkFlow instance should conform to the CommandSet schema.