My thoughts: The Laramie is a much more expensive package than the Big Horn, so the price should reflect that even with the mileage difference. So you're not really comparing the same trucks to each other.
Therefore, I would think about the following: Do I need leather? What about that Alpine stereo with the sub woofer under the back seat? Memory seat? Nicer instrument panel? Keyless/remote start (if applicable)? Am I going to be towing a lot? Because the Laramie has better cooling through the grill.
Then some other exterior things besides the wheels: Is either one of them a long bed? You can spot this by looking at the area between the cab and the rear wheel. Long bed has more distance in that area. What about RamBoxes?
Be sure that it has the hitch and everything already set up. Because you never know! Preferably also with the trailer brake adjustment already installed.
And be sure to CarFax! The low mileage could be because of problems--or it could be because the previous owner(s) didn't drive much. But you don't want to buy a dealer buy-back. They buy them back when they can't locate a problem.
I'm sure that others will be chiming in with other things to consider.