What you are about to read is the gospel and anyone who says otherwise is a know-it-all who knows nothing.
(all disagreements can be sent to Mike, 3rd generation spring maker with nearly 30 years experience, all ridiculous arguments will be listened to)
RATE - Half the difference between the loads 1-inch above and 1-inch below a specified position. Or put an easier way, it is the amount of weight required to deflect a spring 1-inch. The lower the rate, the softer the spring.
LOAD- The amount of weight on the spring.
LOAD RATE- The amount of weight a spring is designed to be supporting at a certain height. Load Rate and Rate are not interchangeable terms.
Now let's put what you just learned to use.
A spring which is designed with a free arch of 6-inches and a loaded height of 1.25 inches when supporting 600 lbs would have a Load Rate of 600 Lbs. and a Rate of 126 Lbs. 6 inches free height minus 1.25 inches loaded height = 4.75 inches of deflection. 600 Lbs. divided by 4.75 inches of deflection = 126 Lb. rate