What's the difference between a rock slider and a running board / step?

Rock sliders and running boards are both aftermarket accessories that can enhance the functionality and appearance of your truck. While they may seem similar at first glance, there is actually a significant difference between the two.

Rock sliders, also known as rock rails, are designed to protect the sides and rocker panels of your truck from damage when driving off-road. They are typically made from heavier gauge materials than running boards, such as steel, aluminum, or chromoly. They are then mounted under the frame and doors and can sometimes incorporate a section that juts out the side (called a kick-out). While they may incorporate a step plate, rock sliders primarily provide protection against rocks, logs, and other obstacles that you might encounter on the trail.

Running boards, on the other hand, are primarily used to make it easier to get in and out of a truck or SUV. Running boards are typically mounted along the side of a vehicle and provide a wide, flat surface that can be used to step on. This makes entry and exit easier, but can also help you access things that are on the roof of the truck. They are convenient, but it is important to note that running boards are not intended to support the weight of a vehicle, let alone a heavy one like an EV. 

In terms of compatibility with the Rivian R1T and R1S, both rock sliders and running boards can be installed after delivery. When deciding between the two it is important to consider how the vehicle will be used. For the Rivian in particular, being the capable off-roader that it is, rock sliders can be the more practical choice for those who plan to take their truck off the beaten path or just want a more rugged look. Running boards then may be a more suitable choice for those who are primarily interested in the convenience and accessibility they provide.

To summarize, the big difference between rock sliders and running boards is their construction and intended use. Rock sliders can often be used as a step, but are primarily designed to protect the sides and undercarriage of a vehicle when driving off-road. Conversely, running boards are specifically intended to make it easier to get in and out of a vehicle. Both can be added to your Rivian, but the choice between the two will depend on the specific needs and preferences of the owner.