Ohhh.. BIG difference.

Diesel is oil.. Nitro is Alcohol

Alcohol is MUCH more volatile. Since their "explosion rate" is MUCH high, this leads to very high Revolution rates.

Diesels do not explode so fast. Most trucks REDLINE at about 2200-2300 RPM!
On the contrary, they produce peak torque at a very low RPM rate.

One deals torque, one deals HP.. thats the ultimate difference!
So, do you want to pull or do you want to scream?
Ram