Tabs are a convenient way to switch from one work area to another
Groups are a convenient way to compare files side by side or above and below each other.
Typically you would do this to view a number of designs at the same time and or select all or part of one design and drag to another.
1 Group 3 Tabs
3 Groups 1 Tab each
Tabs can be dragged from one group to another and back again.
Drag a tab into the current work area to create a new Group
When dragging a design or part of a design from one area to another hold the SHIFT and CTRL key at the same time to COPY rather than MOVE
When dragging from one area to another the “dragged” design will land at its original coordinates where it was situated in it’s workspace. So if both designs are located at 0,0 one will sit on top of the other and will have to be dragged to the new location. This is why I suggest you use the CTRL G (Group command to group all objects in a design before it is moved.