Shouldn't they be the same target?
There is no documentation in the API itself that really explains this.
Best answer by Chandru
virtual-disk - This is the file that is referred by the sas/ide controller in the vm's configuration file .vmx or .xml.
vdisk - this is the file where the data is stored.
In Nutanix on Esxi virtual-disk will point to the .vmdk file (disk descriptor file) in the nfs datastore and the vdisk will point to the -flat.vmdk file.
In AHV the virtual-disk will point to the same files as we don't have separate disk descriptor file like esxi.