Back to basics:
As explained here regarding friction Modifiers in general:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=729029#Post729029
The modern soluble moly additives are primarily Molybdenum Di-Thiocarbamates, or MoDTCs.
There is the Mono-nuclear type, the Di-Nuclear type, and the Tri-Nuclear type. Which one a formulator uses in an oil and how much depends on a number of factors such as application (daily driver, racing) and cost.
In the Tri-Nuclear moly, the core of the MoDTC molecule has more sulfur in order to create or liberate more MoS2 molecules.
This has three advantages, 1) more sulfur for anti-oxidation and hence sludge resistance and 2) more flat plate MoS2 molecules for friction reduction, 3) less MoDTC is needed for friction reduction over the other types of moly.
Think of the MoDTC molecule as a planar object much like a playing card in a deck of plastic coated playing cards.
The flat plate MoDTC molecules tend to stack themselves so that the top cards are sheared off smoothly, thus reducing friction.
(Other friction reducers reduce friction by virtue of allowing their molecular whiskers to be sheared off, much like a mower blade when mowing grass).
In addition, the sharing of Moly MoDTC components with ZDDP molecular components helps the ZDDP reduce wear.
So, as a formulator I have a choice as to which type and additive level of MoDTC to use for the application.