>>96224540
The Grey Knights are the Ordo Malleus chamber militant intended to be the stop gap of demonic incursion that the Emperor can't contain during hi vigil on the Golden Throne, they're secreted and dear being very specific anti-daemon weapons alongside the Emperors efforts.

The Blood Ravens are a disposable, bureaucratic institution during the Scouring and up until m36 acting as an Inquisitorial cudgel to execute the ultimate bureaucratic maneuver the Edict of Obliteration. While the individual Blood Ravens carrying out these actions against Heretical Imperial elements and their fellow Astartes are consistently mind wiped by the Inquisition the chapter's "Secret Masters" of the Ordo Psykana are organizing and executing the operations without any acknowledgement of the details. These actions between m30-m36 are where the Blood Ravens acquire their vast Imperial connections, Inquisitorial seals, and a massive collection of "stolen"(seized) Astartes wargear. The Blood Ravens are the only true Inquisitorial asset with mentions of the the Red Hunters, Red Scorpions, Exorcists, and Minotaurs (SM+Custodian joint ops) all being "declassified" reports fit to publish of the Blood Ravens Inquisitorial actions.