BB spring rate question:

Hey guys, switched to bb springs last week and was happy to not have any rubbing, shock felt smoother for sure just fixing that, surprised AE didn't do anything sooner about it but my question is if the spring rates on the std spring and the 12mm spring are comparable, or will the bb springs still act differently? I was running brown ft and green rear in std, felt good and now with ae 12mm green ft and white rear and the car feels better. Wondering how much of that was going to a stiffer rear spring or was it the big bore springs that helped. Next time out going to try green rear and play a little bit with the shocks. Just trying to learn them better even though the thing feels solid right now.