The Resource Group fields contain the groups to which resources belong.
There are two categories of Resource Group fields.
Data Type Text List (text list field: A type of field whose content is a list of text items separated by the list separator character, typically a comma. Examples include the Resource Group and Resource Names fields.)
Resource Group (task field)
Entry Type Calculated (calculated field: A field in which the value is determined by Project based on information in other fields. Project may recalculate the value automatically or when you specify, depending on your choice of calculation settings.)
How Calculated The content of the Resource Group field for tasks is equivalent to the Group field for resources.
Best Uses Add the Resource Group field to a task sheet when you want to display or filter resources by the resource group.
Example In your project, you have three groups of resources: Plumbers, Construction, and Management. Because you want to review the list of groups associated with each task, you add the Resource Group field to the Task Sheet view.
Resource Group (assignment field)
How Calculated The content of the Resource Group field for assignments is equivalent to the Group field for resources.
Best Uses Add the Resource Group field to the timephased portion of the Task Usage view when you want to display, sort, or filter resources by group. The Resource Group assignment field is available only in the Task Usage view.
Example In your project, you have three groups of resources: Plumbers, Construction, and Management. You want to review all assignments for the Construction group. In the Task Usage view, you apply a filter to show only those assignments for resources that belong to the Construction group. Assignments for resources in the other groups are not shown.