Activate - To activate the selected system task if it is currently deactivated.
Deactivate - To deactivate the selected system task if it is already active.
This article helps you understand right-click options on a system task in a project under the 'Workflows' tab.
Activate - To activate the selected system task if it is currently deactivated.
Deactivate - To deactivate the selected system task if it is already active.