The HD springs are basically a stock replacement spring for musclecars. The super stock springs are biased towards the front of the spring to stop axle wrap up. They also generally have more arch than stock springs so the car will sit hgher.
SS springs come with a 20" front segment (a-body), so if you want to put them in an E or B body you will need different front spring hangers.(Never put in any on an E or B body myself, but that is what I've been told - could be wrong on that)
The SS springs are side specific. The left side has a 1.4 bias control and the right side has a bias control of about 1.7-1.8.
Spring control is the ratio of the stiffness of the front segment of the spring to the stiffness of the rear segment. If the stiffness of the 2 segments was the same, then the ratio would be 1:1 or 1.0. If the stiffness of the front segment was twice that of the rear segment, then the ratio would be 2.0. The average production spring has between 1.0 and 1.4 (on left and right).
SS springs are arched more to give the extra height that you've probably noticed.
There is probably a large difference in the spring rate between the two types. Spring rate is defined as the amount of force required to move the center bolt vertically one inch and is measured in inch pounds. Production springs typically run 85-130 lbs. SS springs run at about 160 lbs. There was a set produced for the hemi manual cars that measured in at 300 lbs.
So to make it short, if you can get that info on your Mopar H.D. springs, that should give you some figures to compare with the SS springs.