The VMware Validated Designs utilize different types of storage, and the "Shared Storage Design" section explains where the SDDC uses each and gives background information. The focus of this section is physical storage design.
All functional testing and validation of the designs is done using vSAN. Although the VMware Validated Designs highly recommend the use of vSAN, any supported storage solution may be utilized.
If a storage solution other than vSAN is chosen, you must take into account that all the design, deployment, and day 2 guidance in the VMware Validated Design applies under the context of vSAN and adjust appropriately. Your storage design must match or exceed the capacity and performance capabilities of the vSAN configuration in the designs.