Manual:Virtualization
RouterOS has two different Virtualization implementations.
Metarouter is created by MikroTik and currently is supported only on RouterBOARD 4xx series (mips-be). Currently Metarouter can only creat RouterOS virtual machines
Xen is based on the Linux Xen Virtual machine project, and currentl RouterOS implementation is supported only on RouterOS X86 systems (PCs). Xen can create Virtual machines of different Operating Systems