The new features on Storage management for Servers, bring a few new terms with it. This short article should help to clarify what are these features.
A group of physical disks that can be managed together.
A collection of one or more physical disks from a previously created storage pool.
A storage subsystem that lets you group disks (drives) into one or more storage pools. You can then create storage spaces from available capacity (free space) in the pool.
A virtual disk created on a Storage Spaces storage subsystem.
Below is the current diagram, from the Storage Management Overview topic on TechNet.