one-piece steel bottom metal adds extra rigidity to the Super Grade’s stock and action for improved accuracy.
Other then that the stocks are the same wood and same general profile, the barrel profile on the super is slightly thicker/heavier as well.

Drew, Different guns. Only thing that is the same is the action. Different barrel, different furniture, different frame and bedding.

Drew, two reasons Sir. Thicker Contour Barrel and Denser Stock and Metal reinforcement for rigidity. Anytime you see Sporter in a Rifle, expect lower weight from the Standard Model. Cheers and stay safe!

Slightly THICKER barrel and different wood grade. Wood can be denser, contributing to more weight. The same goes for an increase in barrel thickness. I hope this helps!