According to the SAP S/4HANA Cloud, public edition Learning Journey1, the correct setup of planner groups and work centers is that both are assigned to a maintenance plant. Planner groups are data that group together maintenance planners who are responsible for planning and scheduling maintenance work. Work centers are organizational units that represent a group of people, machines, or tools that perform maintenance tasks. Both planner groups and work centers are assigned to a maintenance plant, which is an organizational unit that represents a physical location where maintenance work is performed.