Why would the tool itself have a different model number if they are the same tool with just different batteries?
Multiple reasons, first off, to keep track of sales of each kit. Second, distributors would have a hard time figuring out the difference between a compact lithium vs. XRP lithium on the shelf with the same model number, third when someone returns a tool distributors need to know how much credit to give back to the customer. There is a price difference between all 3. I could probably go on, but you get the idea. Nothing to do with marketing.