No, AlphaVM does not emulate OpenVMS. AlphaVM emulates Alpha hardware and can run OpenVMS/Alpha as the guest system.
AlphaVM emulates the whole Alpha system with the CPU, memory, chipset, SCSI controllers disks, etc. OpenVMS runs on the AlphaVM virtual machine as on a real Alpha machine.
AlphaVM can be used to replace a real Alpha system. The applications software will run on AlphaVM unchanged. OpenVMS may need some reconfiguration to run on new virtual hardware.