What are the three major virtual disk file types, and how do they differ?

What will be an ideal response?

The three major virtual disk file types are as follows:
* Thick Provision Lazy Zeroed--Space required for the virtual disk is allocated during creation. Data remaining on the physical device is not erased during creation, but is zeroed out on demand at a later time on first write from the virtual machine.
* Thick Provision Eager Zeroed--Space required for the virtual disk is allocated during creation. Data remaining on the physical device is zeroed out when the disk is created.
* Thin Provision--A thin provisioned disk uses only as much data store space as the disk initially needs. If the thin disk needs more space later, it can expand to the maximum capacity allocated to it.