In The MPS, the comapny level critical components are 
planned and in the mterial master, the MRP type is choosen 
accordingly, this is generally done for single level. This 
is planned seperately and this can be also done using 
interactive planning.

In MRP or time phased planning, the BOm is exploded and 
netting is done and component level quantity and time 
requirements are planned.

Fisrt MPS is done, then MRP is run.