Both Kernel based Virtual Machine (KVM) and Xen are Type1 hypervisors. A hypervisor is used to create and run virtual machines (VMs). A Type1 hypervisor runs directly on the host computer's hardware. Other Type1 hypervisors include HyperV and VMware ESX/ESXi.

KVM and Xen are not Type2 hypervisors. A Type2 hypervisor runs within an operating system on the host computer. VMware Workstation, Parallels Desktop for Mac, and Quick Emulator (QEMU) are Type2 hypervisors.

Type-1 hypervisors are generally faster than Type-2 hypervisors because Type-1 hypervisors run directly on the host computer's hardware and because Type-2 hypervisors have a host operating system that consumes system resources.

Type-1 hypervisors are also called native hypervisors or baremetal hypervisors. Type-2 hypervisors are also called hosted hypervisors.