Hyper-V is a Layer 1 Hypervisor virtualization platform, which can run multiple isolated virtual machines on the same physical host machine. Because many virtual machines may be running on the same physical hardware, you must ensure that enough resources are available. When planning for the server hardware, you should consider the required resources such as disks, storage, networking, and high availability.
Client Hyper-V is the Hyper-V feature that comes with the Windows 8 and Windows 8.1 client operating systems. In addition to having Client Hyper-V available as a role in these products, Microsoft Hyper-V Server 2012 is available as a free download. You can install the free edition on new hosts as the underlying operating system.