Group.Groups selected rows or columns together in an outline. If you have not created an outline, this command creates one ...

Group...Groups selected rows or columns together in an outline. If you have not created an outline, this command creates one for you. In a PivotTable report, this command groups items by category to create a single item from multiple items; for example, you can group days, weeks, or months into quarters for analysis, charting, or printing.