In VMWare, when a snapshot is taken, my understanding is that it creates delta disks, and any writes that occur after the snapshot is created will be written to these new delta disk images, and not the primary vmdk image. This is part of the copy on write functionality which is common between vmware,KVM, and LVM snapshots. If you revert/go to a snapshot, the corresponding deltas are ignored, and if you delete a snapshot, they are deleted so either way you are left reading and writing only to the primary vmdk file again. There is also system setting information and system state information that is saved as well.
Is this accurate, and is it fundamentally the same for LVM and KVM snapshots?