Well Bruce I'll give it a shot. I like to keep it simple.
Torque is what moves you, HP is a bit more nebulous as it is a calculation.
I always think of it this way, you have a 100hp diesel and 100hp gaz vehicle.
in a Diesel Torque is what gets you humongous off the line pull. It's a lot less in a gas engine for a number of reasons which Danny and others can elucidate.