OpenVZ and KVM are two very different virtualization technologies. OpenVZ is OS level virtualization, which is extremely fast, but offers less customisation options (e.g. an OpenVZ VPS cannot run custom kernels, non-standard kernel modules or non-linux Operating systems). For most people, this limitation does not affect them. KVM is "Full Virtualization"; where each VPS runs its own kernel independent of the host. This allows significantly increased support for applications that interact heavily with the kernel; along with custom kernels and non-Linux operating systems.
|Custom kernel/any OS||No||Yes|
|Encrypted Filesystem (FDE) Support||No||Yes|
|Emergency access||Yes, VPS must be booted||Yes - Access to bootloader and console|
|SSD Cached OpenVZ VPS||SSD Cached KVM VPS|