9R-Hexahydrocannabiphorol

HHCP is the hydrogenated form of HHC. To be more specific, HHCP is made by adding two more carbons to its alkyl chain at the tail of the chemical structure. It is believed that the increased length of the alkyl chain, similar to that of THC-P, allows HHCP to have increased bonding to cannabinoid receptors such as CB1 in the brain. Because of THC-P or another hydrogenated form of THC. THC-P has the impressive ability to bind to CB1 receptors in the brain 33 times more than Delta-9 THC. 

Now the comparison of HHCP is more of an analogous situation with THC-P. Both are hydrogenated versions of a THC derivative and, because of it, are believed to be better at binding creating a more potent effect. Anecdotally, it is believed that HHCP may even be more potent than THC-P. There isn't a lot of information on the difference between R and S stereoisomer, but R is energetically more favored. However, if we apply what we know from stereoisomerism of HHC, R isomer might be psychoactive, while S isomer is not.