I just tried it
.
The only indication is
ddb.thinProvisioned = "1"
in the descriptor if it is a thin disk.
Eagerzeroed, zeroed and thick disks have the same descriptor.
Eagerzeroed and zeroed disks (of the same size) even pass a binary comparison.
Thick disks of course don't pass the binary comparison due to their nature.
The only logical answer to me is that part of the CID value distinguishes them.
