The Difference Between ct51264ba160bj vs ct51264bd160bj ?

The only difference between them is that the ct51264ba160bj is DDR3L(L stands for low voltage so it consumes less power) and it runs at 1.35V, while the ct51264ba160bj runs at 1.5V.
If you mix 1.35V modules with 1.5 ones all your memory modules will run at 1.5V, so there shouldn't be any problem.