Pretty much all factory coil springs are linear or straight, which means there is the same distance between each coil. H&R uses progressive ones that have a variable spring rate which is reliable on all types of surfaces. Vehicle equipped with the leaner type do not have as much versatility or control as these from H&R. H&R springs come in many different styles that increase the vehicles stability by lowering its center of gravity.
The progressive spring rate allows for extreme comfort on flat surfaces but can quickly adapt to uneven road surfaces along with twists and turns. H&R components do this much better than your OE ones by decreasing body roll. Body roll is always encountered with OE components since they are linear. Linear provides the same exact driving capabilities on all surfaces, while H&R proves themselves on all types of surfaces and can adapt to any situation.
The linear type can also be very harsh and has no versatility. H&R can be soft on the highway but when taken through the twists and turns, they will become firm and provide great feedback for the driver. The faster you drive, the more feedback H&R components will give you, something that linear ones are not capable of.
Factory shocks do not match that well with the progressive type, though. Although the H&R OE sport can be used with factory shocks, the others are not recommended to do so. The vehicle needs a shock that can handle a variable spring rate in which the OE cannot. The OE shock is only meant for that specific spring that it has installed which is sometimes linear. If you want to rely on something that will benefit you in both even and uneven surfaces, than H&R is the way to go.