SAP System copy is one way to copy an SAP system into other of one or more following options:
- server / machine platform
- other SID (system ID)
- operating system (Linux, Sun Solaris, HP-UX, IBM-AIX, MS Windows)
- database product (MaxDB, MSSQL, DB2, Oracle)
Generally if operating system and database between source system and target system are same, it is called homogeneous system copy. If one of both criteria differs, it is heterogenour system copy. In short it is called homo or hetero. If someone say about migration or technical migration, most of the time it refers to hetero. There is also logical or business migration like one SAP customer company move its SAP from or into another existing SAP services, such as one company leaves its holding company or join another company and need to move its business process into other existing SAP system.
For more information regarding this http://service.sap.com/osdbmigration (OS/DB Migration)