How are motorcycle torque and horsepower different?

Torque is the measure of pressure on the twisting action of the crankshaft.
It is usually measured at 1 foot.
If your bike has 70 foot pounds of torque @ 3000 RPM,
The motor can hold 70 pounds of weight 1 foot from the crankshaft while running at 3000 revolutions per minute.
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Horse power is the measure of the amount of work the motor can do in a certain amount of time.
So if your motor can develope 45 HP @ 5500 RPM,
The motor can do work equal to the strength of 45 horses ( which has a formula to determine, Not just any horse) while turning 5500 Revolutions per minute.
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Torque is usually mentioned when talking about a motor that can do a lot of work, not necesarilly run really fast.
Horse power is usually mentioned when talking about speed.