The result of workflow can be an entry in the inbox of your end-user, to which "workflow" presents itself. The terms Work Item and Workflow shouldn't be mixed... as they do not mean the same. The term Workflow is often used to refer to the inbox entry that "is produced by workflow", which should really be called a Work Item. A Workflow could consist of several work items, and a lot of confusion could be avoided if the difference between workflow and work item is clear...
