Although roof racks and roof rails share similarities, the primary distinction lies in their mounting direction onto your vehicle. The roof rails are parallel to the length of the vehicle, extending from the hood to the trunk, while the roof racks are perpendicular to the car, extending from the driver's side to the front passenger's side. It is important to note that roof rails are usually installed by the manufacturer during production, while roof racks are typically added on as an aftermarket accessory once the vehicle has been purchased.