The difference of Torque and Horsepower.
Torque is a measure of force over distance. Horsepower is a rate in which torque is being done.
Torque = force * distance
lbs ft
Horsepower = [(force * distance) / time] / 550
lbs ft sec
One could move a box weighing 550 lbs 1 foot and would be exerting 550 ft * lbs of torque. It wouldn't matter if he took 1 second or an entire day. The rate or amount of horsepower this person was using, would depend on the amount of time it took to move the 550 pound box 1 foot.
If it took 1 second to do this work, then the person would be using 1 horsepower.
horsepower = [(550 lb box * 1 foot) / 1 sec] / 550 = 1
If it took the entire day (86400 seconds) to do this work, then the person would be using 0.000011574 horsepower.
horsepower = [(550 lb box * 1 foot) / 86400 sec] / 550 = 0.000011574