What is KVM?
KVM (or Kernel-based Virtual Machine) is a Linux kernel module that caters a framework for tools like QEMU for virtualization platform. It is identical to Xen in many ways which allow you to run any Operating System and is optimized for running with low-level kernel settings.
You can also install Operating System on your own with an ISO file such facilities are provided by a few providers only. It runs only on hardware that supports VT technology (Hardware Assisted Virtualization).
What is XEN?
Normally there are 2 types of hypervisors, type 1 runs on the host machine directly and types 2 runs over an existing operating system. Xen comes under Type 1 Hypervisor.
Due to this Xen can run any Operating System like Windows and different flavours of Linux. Kernel upgrade, adding additional modules etc is also possible in this Virtualization as it is running on a Fully virtualized Operating System.
Such a setup requires much overhead than Type 2 virtualization because it has to match a lot of hardware features along with the Operating System. To decrease the overhead Xen implemented paravirtualization later. It came with a lot of improvements with the same operations.
Hope my answer will help you to more understand the difference between XEN and KVM.
The main difference between KVM and Xen is that KVM is a virtualization module in Linux kernel that works similar to a hypervisor, while Xen is a type 1 hypervisor that allows multiple operating systems to execute on the same computer hardware, simultaneously and regarding hosting services you should get best hosting from fresh roasted hosting at an affordable price with good 24*7 American support.