Grouping allows you to view your project's data in different ways. The grouping icon is located top-right of the membership list, just left of the resourcing plans.

No grouping is the default option in which every role is shown as an individual row. This is the "original way" of showing the roles as it has been like this for most of Silverbucket's lifetime. The only rule is that the unassigned roles are separated from assigned roles.

Group by people sorts the project roles by people and shows data based on these individuals. Unassigned roles are shown as a separate Unassigned section (orange rectangle below).

In the example below we can see that Brown Elijah is resourced to do 70% workweeks: 50% consists of Officer work and 20% consists of Specialist work (blue rectangle below).

Group by role grabs both the unassigned roles and assigned roles and bulks them up based on the role. When viewing the allocations in weekly & hourly mode you can see the resourcing plan for certain roles individually.

Group by task is a little different from the others as it takes the role's metadata into account -  specifically the Task value entered for the role.

In the example below we can see that the Preparations task requires work from Specialists but also has an Architect involved.