ES44DC vs. ES44AC

What, if any, are the external differences between the ES44DC and the ES44AC? I can’t see any in the pictures I’ve seen, both seem to have the large box behind the fireman’s side of the cab, like the AC4400CW. What is the purpose of this box on the DC? I know it normally houses the rectifiers on the AC model, but what then on the DC?

And will CN’s models have the large box? I know they cut down the height of the box on the Dash-9.

Actually the box on the ACs is for the inverters. I don’t know what it houses on the DCs.