There is no discrepancy. You just haven't learned enough about it yet. We can help.
Hey, KFDiesel. The maximum length of a particular cartridge is established by international standard, and the institute called SAAMI (Small Arms and Ammunition Manufacturer's Institute) keeps the standards. That way gun and ammo manufacturers are on the same page when they make their products. That's what the maximum is all about.
The minimum in your load data is established by the lab that loaded and shot the test loads listed on your particular data sheet, and are specific to the particular loads listed on that sheet. If you load a bullet shorter (which reduces the available volume inside the case) it leads to more pressure. So you don't want to go shorter than the minimum length listed on your data sheet, but you can go longer (as long as it fits in the magazine). If you pick up another data table, be sure to pay attention to the minimum length for that data table. You can always go longer than the minimum, never shorter.
Go get a real book and read all about it. It's really pretty cool, and you'll learn a lot. ABC's of Reloading, Speer, Hornady, Lee, Lyman and Sierra all are excellent books. They aren't expensive, and you really need the information.