Couldn't tell you for sure but typically, heavy duty typically means different spring rate and shock size and or valving. More times than not, the springs can carry a heavier load and shocks are designed to not fade with hard use. Of course, ride quality is 100% subjective so I couldn't tell you if the ride would be better or not for you specifically.
Thanks. I figured heavy duty was not a bad idea since I got the heavier diesel. I didn't know what was different with "heavy duty". All JL's I've checked have normal suspension except Altitude. I'll know soon. Jeep JL Sport Altitude is scheduled for delivery next week.