Besides the fact that the CAT D series offers a truly pressurized cab, reversing camera, speed sensitive ride control, foot throttle, self leveling both up and down, better side visibility (look at their brochure with the loader in the carry and you can see that it is hard to see down to the tracks), more engine torque at 500rpms lower and more hp at a lower rpm means better fuel, 4 more hp, way more reach at truck bed height (the 323D can't even get its mast up to the pallet when the pallet is about a foot off the edge of the truck), 10 more degrees of dump for sticky materials (the Deere only dumps to 42 degrees), an actual emergency rear exit (without having to kick out the window), the ability to actually/easily service the engine without having to raise the loader arms up (ever wonder why the JD machines always have their service panels and cab raised up at trade shows? Because it is a PITA to take the engine access panels off when the loader arms are down. It would suck to have to take them off every morning to check air filter, water separator, oil, etc.), dead engine loader arm lower with an actual accumulator, 6" narrower, 3" more height to bucket pin, almost 9gal larger fuel tank, almost 2.5mph faster 2spd. Other than that, not much difference between the two.