On the terminology of commode and coiffure, the sources are not agreed. Some say that the commode meant a cap, while coiffure could denominate either the cap or the combination of the cap and its accompanying hairdo, just as the English "head of lace" usually referred to the cap.
Another source uses the term commode for the high hairdo that appeared at the same time as the fontange, and in another place for a bum roll. It's quite possible that period terminology was just as muddled.
Depending on the decade you look at, the commode, if we agree that it's a cap, could take on just about any shape, e.g. at the beginning of the century the lace-surmounted one we nowadays usually call fontange.