According to the spec sheets, both have 1:8 twist bbls, both are threaded. The big difference is bbl length (16" vs 22") and caliber (5.56 vs .223).
On the caliber front, you can shoot .223 in a 5.56 chamber. 5.56 is not necessarily the best in a .223 chamber though. You may get FTE or other issues. The looser 5.56 chamber is not as conducive to pin point accuracy as the tighter .223 chamber. We're talking a small difference though on the order of maybe 0.25-0.5 MOA.
On the length front, the longer bbl will give more velocity which is important for maximum fragmentation distance with the 5.56/.223 round if you're using it on meat. A 16" bbl with ball ammo will give 3125 FPS, which gives good tumbling and frag out to somewhere around 100ish meters. 20" will get you 3250 FPS which extends the high probability of frag range out to 150ish meters. Premium ammo like MK262 will frag at lower velocities and longer ranges. You get little benefit beyond 20".
So it all depends on desired usage. The Predator will be a better varmint rifle, with mayble slightly better accuracy and longer effective ranges on meat. The Ranch will be handier and usable with a wider variety of ammo. I would personally opt for the Ranch as I have a ton of 5.56 ball stocked up and appreciate the handiness.
