The PredatOBR is designed as a fully capable suitcase rifle that can be completely broken down and carried in a compact case or backpack, reassembled for firing and exhibit minimal shift in point of impact. Outfitted with the same barrel as the OBR, which is a nearly constant taper from the chamber to the gas block and straight from the gas block to the muzzle at roughly 0.75" IIRC, and has the PST "Port Selector Technology" gas block for switching between suppressed and unsuppressed shooting. It includes a barrel nut wrench specifically designed for the PredatOBR barrel nut.
The PredatAR is a lighter weight chassis with a lighter weight and slimmer profile barrel, which crowns to a thicker shoulder at the seat of the muzzle threads. The handguard is "fixed" which is to say it requires hand tools for disassembly, as opposed to the PredatOBR's Quick Detach design and included barrel nut wrench. The PredatAR has a "normal" style of low-profile gas block that is non-adjustable.
Both are excellent choices in the 7.62 platform.