Rumour has it that one volume of Zi Wei San He Si Hua was stolen from the imperial palace. The thief had pilfered the San He volume but omitted another volume on Si Hua Zi Wei Dou Shu (“ZWDS”). When the Emperor found out, he commissioned his imperial astrologer to make up a fake version and release it to the commoners.
This may be the reason why the San He system is based on two ancient books titled The Complete Book of Zi Wei Dou Shu and The Complete Collection of Zi Wei Dou Shu. Some of the differences amongst them are glaring.
The Si Hua ZWDS remained exclusively in the palace until close to the fall of the Qing dynasty when it became available to the public and therefore is clearly a much more exclusive system of study.
Are they different?
A good practitioner should integrate both systems for a more comprehensive reading since the basic charts for both systems are the same and yet the strengths of each system differs.
The San He system uses more stars (up to 108) and is determined by combinations of stars in different domains to derive a very comprehensive reading. The Si Hua system on the other hand, is heavily dependent on the energy dynamics of flight path of the 4 Transformed Lu, Quan, Ke & Ji stars to come up with a reading. Thus it can do with uses much fewer stars, 18 to be exact, for its reading. I am one of the rare practitioner that integrates the practice of the hybrid of both systems and use 37 stars for analysis.
A direct result of these, is that the latter system requires less memory work but more challenging visual inspection of the flight path of those transformation stars. In addition, when flight path is brought into the picture, there is better indication of the level of energy and hence useful for event prediction. Comparatively, static readings of star combinations typical of the former system generally forsake event prediction for qualitative reading. Generally, students that are more visually gifted and study smart (because they have less stars combinations to remember) will prefer the latter system.
Both systems should be used interchangeably to provide greater clarity in reading and prediction although I firmly believe a destiny consultant provides more value to his clients by advising them the time of an event happening rather than the qualitative characteristics of matters or events.
In any case, historically the Si Hua system has remained an exclusive practice of the Imperial Court until only the fall of the Qing Dynasty while the San He system has been propagated by commoners. This historical perspective sufficiently explains why there are much more Zi Wei Dou Shu practitioners of the San He system but yet not necessarily a better system.