[ovirt-users] Question: How does ovirt storage domain differ from VMFS?

Hello, I was asked the other day what file system oVirt uses to store virtual machine images and how it differed from VMware VMFS. I had to admit that I didn't quite understand this aspect of oVirt. I've had a look around but haven't found an answer. I was wondering if someone could explain at a high level, how the underlying oVirt VM storage domain differs from VMFS? What file system is used? Does it use a file system at all? Thank you.