Ah yes. Somewhere on the forum there is a section for suspension for Proteges. It's call the Protege Based Rims / Tires / Brakes / Suspension forum. With the spring guide. http://www.msprotege.com/forum/showthread.php?t=58798
If you're talking about stock springs, I know there's a difference, but there aren't any specs in the guide for the stock P5 springs.
01 and early 02 2.0 *automatic* sedans uses different front springs (B27R-34-011A) while all other model variations uses the same front springs... this changed later on and everything used the same front springs however
P5s with sunroofs uses different rear springs also (B26H-28-011)... P5s without sunroofs uses the same rear springs as the ES though (BJ3D-28-011)
well, the sunroof has a pretty big effect on the balance of the car. It puts a lot of weight up top, raising the center of gravity. I'm sure the stiffer springs are necessary to control that added motion.