I meant to say if the beds were interchangable. There is a side step for sale here but I rather have a straight bed. I was just wondering if the frame were different because in the future I would want to change the bed
Yes - the beds are directly swappable. However ...
The StepSide setup includes two skirt pieces (one in front of the wheel well; one behind it) that are not part of the bedsides. You may want to make sure you get the skirt pieces to prevent it looking weird.
When you say you would want to change to a fleetside bed in the future - you mean swap out for a fleetside whole bed, not convert the StepSide into a fleetside, right?