there are several things to consider here:
one is engine torque at low rpm, like clutch engagement when you start pulling a load or you are inching along in traffic or through a parking lot
two is peak torque both in number and in RPM
third is area under curve and fourth is torque at wheel, which is affected by gearing and tire size.
Some medium duty and heavy trucks quote torque at clutch engagement. I have never seen this for Fuso. It is usually a very low rpm, like under 1000. This tells you a lot about the characteristics of the motor as the turbos have not built boost yet and the engine is not revving or into its power band.
Torque peak for a Cummins ISB is around the 1600-2000 RPM mark in a stock motor. After this RPM, torque will stay the same or begin to drop. This is not the HP peak, but the torque peak. Now I know people will chime in and say their engine makes this or that at this RPM, but we are talking very basic/general concepts here.
Area under curve has to be figured using calculus and basically tells you what the power band feels like. You can have a torque curve that looks like a skateboard ramp from the X-Games with 1000 pound feet of torque at the peak, but the truck is going to drive like crap because of where the torque peak is and the shape of the curve. You want a torque curve that is relatively flat or gently climbing and dropping, while a HP curve should look like a hill or mountain, climbing steadily and gradually from point to point. A motor making 500 foot pounds of torque at 1600 rpm is going to feel very different than a motor making 500 foot pounds of torque at 5000 rpm, like a turbo charged gasoline engine might. So 500 foot pounds is not just 500 foot pounds.
Finally, engine torque only tells part of the story on what you feel and how the truck behaves. A good example is a stock Landcruiser with stock tires and then a lift kit and 38" tires on the same truck. The engine numbers have not changed and the gear ratio has not changed but the behaviour of the truck will. It will feel very slow and sluggish. The opposite will happen if you installed a 6.17 ring gear into a stock truck. Great performance off road, RPMs will rise quickly and you will have much more torque at the wheels as a result of gear/torque multiplication, but your RPMs will be screaming when you are driving down the hwy. Torque multiplication and driving characteristics on and off road can also be tuned with transmission or transfer case gears.
It is therefore possible to lower peak engine torque between models, lower gear ratio (5.29 to 5.71 for example) and have the same torque at the rear tires, which is what you feel pulling a load. It gets kind of complicated and you still have less torque from the motor, but its all about how and where that tells the true story of drivability. If your truck had an automatic transmission things like torque converter efficiency, slip or locked up, etc will also affect drivability.
So, the simple answer is they need to be compared back to back in a shoot out and you really need to go drive one to see how it behaves because a PDF or chart only tells a very small part of the story.
For the technically minded, HP is a completely man made number, its made up. It could just as well be fluggelbinders. Torque is a moment acting on something, a twisting force or a leveraging force. Using a simple equation HP is calculated from torque and RPM. HP is work over time. If you look at the two extremes you may understand better. HP = (TQ x RPM)/5252
A race car like an Indy Car or Formula One car makes incredibly high (800-900) hp and comparatively low (200-300 foot pounds) torque. The reason is two fold. One they dont need torque to move a 1500 pound race car down a track really fast and two the torque numbers are actually pretty constant but the engines rev as high as 18,000 RPM. So using the HP equation its easy to see that HP is a function of RPM. Want more power, rev the engine higher. This is an isolated example but a simple explanation of how 900 hp is achieved from a 2.4L Naturally aspirated V8 engine.
Now the other side of that is a big over the road truck, an 18 wheeler or a Lorry. Those trucks probably only make 300-400hp, accompanied by 1000 - 2000 foot pounds of torque, probably very low in the RPM range.
One reason is basically the same as above with the F1 car. Heavy truck engines dont rev very high at all, so they dont have an opportunity to make high HP. Making high HP at low RPM is pretty tough. Making torque at low RPM however is pretty easy. Trucks operate at low RPM, high torque for pulling loads, trailers, towing a boat, whatever. An F1 car would be terrible at this even though it makes 900HP. Trucks typically have low gears all around as well (transmission and rear axle) You would hardly ever see a heavy truck with a 3:1 first gear or 3.73 in a ring gear because the torque multiplication would be lost. They may have a 13:1 first gear and a 7 something or 6 something ring gear. They have huge running gear to put (potentially) a hundred thousand foot pounds of torque (or more) to the wheels. That is what it takes to move 60-100k pounds down the road.
