The NCEP multi-IC and multi-model short-range ensemble forecasting (SREF) system has been operationally running since May 2001. Ensemble members grouping by model is a main concern from field forecasters. To overcome this problem, a new physics ensemble system which addresses more in model physics diversity has been developed and is now under testing and evaluation. The preliminary results show that adding physics diversity improves the SREF system in general. This presentation will report some of our findings in detail from the comparison study between the multi-IC ensemble and the multi-physics ensemble within short range in time (1-3 days). For the current NCEP SREF system and products, please see the following web site: http://wwwt.emc.ncep.noaa.gov/mmb/SREF/SREF.html.