Hi melly,
Basically the effect of LIKE and TYPE is the same. The rule is when referring to a data dictionary object, use type; when referring to data storage already allocated, use like. If you need 2 identical itabs, define the first one using types (pointing to table fields defined in the dictionary), and define the second itab by one statement: Data: itab2 like itab1. To meet the SAP guideline, take an older ABAP program and mass replace all the LIKEs with TYPE. Typically only a couple of statements will need to remain as LIKEs. TYPE becomes more important when implmenting ABAP classes (OOP).
Mike