Benefit of "Plant" vs "Warehouse" argument

My company is comprised of 2 divisions in two different states. We have Epicor 9 but for whatever reason when the 2nd location was set up, it was set up as a "Warehouse" and not a "Plant". I'm looking for good reasons why my company should want to correct this and set up each manufacturing location as a Plant. I'm convinced we are living with some serious drawbacks because of this arrangement but i need some concise arguments to take to management.

Thanks for your help!