Hi Matt,
If you look at an ADL from the bottom, what you will see is a trigger guard that only covers the trigger. There is no hinged floor plate or removable magazine, just stock wood in front of the trigger guard. This is called a blind magazine and can only be emptied by cycling the action. On a BDL you will see the trigger guard and a HINGED floor plate that you unlatch to dump out the cartridges from the bottom and the HINGED floor plate swivels and stays with the gun. The hinged floor plate is a great feature for hunters so they don't have to rack the bolt for each round to empty the gun after the hunt. Much safer.
The Choate stock has a blind magazine like the ADL with no hole for the hinged floor plate. If you want to use the hinged floor plate of the BDL you have to hog out the bottom of the Choate stock so the BDL floor plate fits. The stock is made to be a blind magazine thus no cutout for the floor plate. It's not as easy as it sounds as the floor plate must be fitted fairly precisely. Thus the notation to use a gunsmith. I'm not sure but I think you can use the magazine box from the BDL and you would have a blind magazine just like the ADL. But worst case, you might have to buy an ADL magazine box if your trying to put a BDL in a Choate stock and don't want to hog out the stock for the BDL floor plate.
The DETACHABLE magazine is a different setup entirely. It has a REMOVABLE magazine that you can remove and put in your pocket with the loaded rounds still in it. It allows you to carry extra magazines just like an auto pistol. Any stock that says it fits an ADL (box magazine) will have to be modified (read hogged out) for a BDL floor plate or a detachable magazine to fit. I expect the stocks that say they will fit a detachable magazine or a hinged floor plate are hogged out already and wouldn't fit a box magazine ADL. You would have to buy the BDL detachable magazine retrofit kit that would include the plate that isn't hinged and has the hole and latch if you wanted a detachable magazine. Unless of course you already have a 700 with a detachable magazine. Then you would already have the magazine and proper hardware.
Hope this clears this up for you,
Dave