Q: Why have snapshots been renamed to checkpoints inR2 Hyper-V?
A: There was always an inconsistency in naming. While Hyper-V used the "snapshot" nomenclature, System Center Virtual Machine Manager used the "checkpoint" nomenclature.
Additionally, the use of snapshot caused confusion related to volume shadow copy service (VSS) snapshots used in backups. Therefore in Server 2012 R2, snapshots in Hyper-V have been renamed to checkpoints to provide consistency of naming and avoid confusion.