The direct comparison of State Machine is to Workbench Moderation.

The main difference between State Machine and Workbench is that State Machine is extendable and exportable through plugins. Workbench is mainly administered through the user interface and is currently not exportable.

For developers, State Machine events and states can be defined through extending the base class. A basic workflow interface within Drupal's default revision architecture is provided by State Flow.

The user interaction of State Machine is purposefully simplistic. For those who are looking for a more robust solution that can be configured through the Drupal administration area should look at using Workbench.