Monitor Capacity
When you monitor space for a folder, you can see the total usage of the folder and its distribution into volume usage, snapshot usage and unused reserve. If the folder has a limit, you will see the limit as well as the volume count.
When you monitor space for a volume, you can see the volume usage, unused reserve, free space, and size. It also shows you the space used by snapshots of this volume and the total usage of the volume.