Not a heck of a lot as far as I can tell, I like the looks of the CDL stock better, and I think they come with the new X-Mark Pro trigger. Basic design is still the same.
I think the new BDLs have the x mark trigger too. Pretty much the only difference youre looking at it the CDL has somewhat of a satin finish on the stock where the BDL is a gloss finish and the BDL has iron sights mounted to the barrel where the CDL has no sights mounted and is not tapped or drilled to add iron sights. I own a BDL but to me the CDL has a sportier look since it doesnt have iron sights.