SmartOS is designed hypervisor OS, it is as if Proxmox.
And VMs are separation by two layer, Zone and bhyve.
VMs run on bhyve, bhyve runs on zone, this model is more secure than Proxmox.
And SmartOS uses bhyve for virtualization, user can choice difference hypervisor as Xen and KVM.
And SmartOS is developed by Sumsung, so project has continuity!