Size
The Dogue de Bordeaux is a little larger on average: about 54 kg (120 lb) as an adult, against 45 kg (99 lb) for the Rottweiler.
Shedding
Their coats shed differently: the Dogue de Bordeaux sheds through the year, the Rottweiler moults most as the seasons change.
Grooming
The Rottweiler needs more grooming, brushing a few times a week, where the Dogue de Bordeaux needs a brush once a week.
Temperament
They differ most on intelligence (Dogue de Bordeaux: easy-going, simple routines; Rottweiler: learns readily, likes games) and on sensitivity (Dogue de Bordeaux: average; Rottweiler: hardy, takes a busy home in its stride).
Alike
Both are rated the same on affection: a lap or leaning dog.