Identical worksheets are needed prior to using the Consolidation feature, creating a sum across worksheets or using the Paste Special Math features to create summary worksheets. By grouping the worksheets first and then adding rows or columns, changing headings and other formatting operations, you ensure that the spreadsheets remain uniform.
You can use the Fill command in the Editing Group on the Home ribbon bar to fill information across worksheets when they are grouped. For example, if you add a few worksheets to your workbook and you can to copy parts of one worksheet to another, you could use copy and paste, however, this could take several operations to perform. By grouping the worksheets and using the fill command, you could quickly copy parts of the original worksheet to the new worksheets inserted into the workbook.