In VMware ESXi vSphere, the virtual CPU consists of the virtual instruction set and virtual memory management unit (MMU). The virtual instruction set is a list of CPU-executed instructions. The virtual MMU is mapped between the virtual address and physical address in the physical memory. The combination of the virtual instruction set and memory is called monitor mode. The VMM can identify the ESXi host hardware and its CPU model. Then it chooses monitor mode for the virtual machine on that hardware platform. It can also configure the monitor using software techniques, hardware techniques, or a combination of both techniques.
The following table lists the difference between CPU software virtualization and hardware virtualization: