OpenStack and KVM are two different virtualization technologies that differ in their virtualization levels and functions.

　　OpenStack:

　　OpenStack is an open source cloud computing platform that provides a complete set of Infrastructure as a Service (IaaS) solutions, including virtual machine management, network management, storage management, etc.

　　OpenStack adopts a layered architecture, consisting of multiple components, including computing (Nova), network (Neutron), storage (Cinder, Swift), identity authentication (Keystone), etc.

　　OpenStack can manage a variety of virtualization technologies, including KVM, VMware, Xen, etc., so it is a cloud computing solution that can support multiple virtualization platforms.

　　KVM:

　　KVM (Kernel-based Virtual Machine) is a virtualization technology based on the Linux kernel. It allows the creation of multiple virtual machines on a physical server, with each virtual machine running its own operating system.

　　KVM utilizes the virtualization features of the Linux kernel to virtualize and manage hardware resources by running the virtual machine on the host as an ordinary process.

　　KVM is a complete virtualization solution that provides complete virtual machine management tools and APIs to easily create, start, stop and manage virtual machines.

　　the difference:

　　OpenStack is a cloud computing platform that provides a complete cloud infrastructure management solution, while KVM is a virtualization technology used to create and manage virtual machines.

　　OpenStack can manage multiple virtualization technologies, including KVM. KVM is one of the virtualization options of OpenStack.

　　OpenStack provides a higher level of abstraction and management, including management of network, storage and identity authentication, while KVM mainly focuses on the creation and management of virtual machines.

　　OpenStack can be used to build public and private clouds, while KVM is mainly used to create virtual machines on a single physical server.

　　In summary, OpenStack is a more comprehensive and complete cloud computing platform, while KVM is a virtualization technology that can be used to create and manage virtual machines on OpenStack or other platforms.