In this work, we investigated the hydrogenolysis and hydrocracking of PP, LDPE, and model alkanes that co-occur on a low-loading Ru/TiO2 catalyst. Ni/TiO2 was also studied for hydrocracking as a noble-metal-free catalyst. We show that the superior activity and selectivity of hydrocracking to hydrogenolysis make the bifunctional Ru/TiO2 more suitable than monofunctional Ru catalysts for PP conversion. Lower hydrogen pressure and more branched products increase the tendency for the reaction to occur through hydrocracking, which can also be effectively catalyzed by Ni/TiO2. The unexpected bifunctionality of Ru/TiO2 was attributed to auto-adsorbed carboxylates on TiO2. This work elucidates the co-existence of the two routes on a bifunctional catalyst, the relationship and comparisons between them, and how the mechanism of polyolefin upcycling is altered by reaction conditions and catalysts. Also, the results on the Brønsted acidity of TiO2 opens brand new opportunities in developing novel acid catalysts.