Tasks and Task Groups 
Within workflow you use tasks for the following purposes:
To use methods of an object type in a workflow (single-step task)
As a framework for defining a workflow (multistep task)
You use a task group to collect tasks used in a common context.
Note
Within SAP Business Workflow the terms task and single-step task are treated as equivalents, as are the terms workflow and multistep task. Only when it is not clear from the context are the terms single-step task and multistep task used.
To create a single-step task, you must know the methods to be executed with the task (see also: Maintenance of Reference to Object Method).
To create a multistep task, you must be familiar with the business process you wish to map as a workflow definition, its flow and its individual steps. When a workflow is created, the associated multistep task is created automatically as well.
You can process tasks of the following types:
Standard task (single-step task, task type TS)
Customer task (single-step task, task type T)
Workflow template (multistep task, task type WS)
Workflow task (multistep task, task type WF)
Task group (task type TG)
Note
Only cross-client single-step tasks (= standard tasks) and cross-client multistep tasks (= workflow templates) can be created now.
When a workflow task/customer task is copied, the task type is changed automatically to workflow template/standard task.
For more information, see Creating and Maintaining Tasks. Also see the relevant task type: