RHEV : VM clones / templates clones

Hi,

I would like to know what really happens when using the different cloning methods (I didn't find any details on it in RHEV docs) :
- cloning a VM
- cloning a VM from snapshot
- creating a VM from snapshot

In what cases the hard disk and machine are fully independent ?

When you simply, clone a VM, it seems the same hard disk virtual image is used, does it mean only the difference from tihe original VM is written ?

What is the safer method ? I've heard many related experiences with virtualization softwares, when making "linked clones" of VM resulting in a lot of troubles when cloning multiple time with only differences written (a lot of time actually) and when deleting the original VM...I would like to avoid this to happen, any suggestions ?