M391A4G43BB1-CWE and the M391A4G43AB1-CWE introduced above memory stick is only one letter difference, not only the part number looks almost exactly the same, its parameters are also roughly the same, the same high frequency (3200), large capacity (32G), for the server market (ECC) DDR4 memory module.
Basically, the two can be infinitely aligned, but if you are using dual channels, it is still recommended to use the same memory module of the material number to minimize the impact on compatibility.