From a note in

From a note in metalink Product Development states essentially there's no difference between MPP and MPS Plan. Details: A. In 11.5.9, we had three plan types: DRP (Distribution Plan), MPS (Production Plan) and MRP (Manufacturing Plan) B. In 11.5.10, we had three plan types: MPP, MPS and MRP. We changed the DRP name to MPP. Why? Because in R12, we introduced a new Distribution Planning engine and having the term DRP used for the old plan type would have caused more confusion than MPP. By 11.5.10, there were no essential differences between MPS and MPP plan types. There is one case using MPS which considers the profile option MSC: MPS Auto-Firm Planned Orders. But other than that there is no real difference. So basically you need to decide if you want to use MPP or MPS for the Hub Plan. But make sure you setup the Organization Item Attributes in the MPS/MRP Planning tab for Planning Method correctly