difference in linear and progressive springs

[J-rod]

http://www.stangsuspension.com/store...tesarticle.asp


so i was checking out different spring rates and comparing the FMS to stock mach 1 and bullitts and noticed the main difference in mach 1 and FMS C's is the rear in the mach is linear and rear in C's are progressive.


so whats the difference on the street? looks like the mach 1 and C's would be very comparible for a street car.

edit #2 - the lower the number the softer the spring? or vice versa