It was just their way of naming their models.The ADL was the "cheaper" model,it has actually been replaced with the SPS (Special Purpose Synthetic), it had a plain stock with no floor plate.The BDL was a little nicer with nicer wood on the wood stocks and had a floor plate.The CDL is very nice,very nice wood usually with an ebony tip on the stock,deep rich bluing and just a nicer looking rifle.I believe (somebody correct me if I am wrong) but the actions and barrels are all the same,just different bluing on them.Nice thing is,that if you buy the ADl you can swap and switch stocks and all between the nicer models.Hope this helps.
Tim