Take a look here
vSAN for VDI (Virtual Desktop Infrastructure) | Horizon 7 Features | VMware
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All-Flash or Hybrid Architecture
vSAN can be used in all-flash architecture in which server-attached flash devices provide both caching and data persistence for extremely high and consistent levels of performance or in a hybrid configuration in which server-side flash devices are pooled to provide a read/write cache and server-attached HDDs provide data persistence.
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VSAN for Desktop I'm pretty sure is the same thing as vSAN for VDI, I can't see why there would be different ones, plus I've never head of vsan for vdi, other than this page I think its just a different name for the same thing.