I think that both accomplish about the same thing by different processes. If you have oil leakage that you want to attempt to cure by reconditioning the seals, go Auto-Rx--don't know if Neutra has this effect.
You can also add 1/2 oz. of Neutra or 1 oz. of Auto-Rx to your power steering, drive several hundred miles, then drain and refill a couple of times. 6 oz. of Auto-Rx in your automatic transmission (I don't know the dosage for Neutra), drive for 1000-1500 miles, then completely flush and renew the ATF will clean and free-up the transmission valving, etc. One oz. per gallon of Neutra in your fuel will clean the fuel system, injectors, and combustion chamber--works well when done concurrently with the crankcase cleaning.
Ken