The definition of a workflow, according to Wikipedia, is a "depiction of a sequence of operations". When taken at face value, a workflow is typically something you want to automate in Drupal. In other words, what we're talking about is Drupal Automation and my guess is, you'll want to automate things in Drupal based on certain events.
The confusing part of Drupal automation is the fact that you need to know what works together to accomplish such automation. With the modules of Workflow, Actions*, Triggers* (* Part of Drupal 6 core) and Rules, it can be quite confusing when it comes to automation.
