What is the difference between "planned consumption" and "Unplanned consumption"? Can safety stock calculation be done on either of these?

While customizing movement types (OMJJ) it is defined as to which set of consumption values gets posted during the material movement. For some it may always be the total consumption and for some it is always the unplanned one and for some it is dependent on whether the issues were done with reference to a reservation ie., a planned consumption. The way these consumption values are taken into account in MRP is defined in the customizing of MRP types. 
For Reorder point planning (VM) the total consumption is used to calculate the safety stock and the reorder point. 
For Forecast based planning (VV) the total consumption is used to build the forecast which will be used to compile the order proposals. 
For Deterministic MRP (PD) the unplanned consumption is used to calculate the forecast which in turn is added to the actual demand.