I have both ducks and chickens. Here are a few things I can think of.
~they may or may not be able to be housed together, be prepared to give them a separate house and run from the chickens
~they can be housed in close proximity to chickens
~duck housing is easier to build/make than a chicken coop, a dog house would work, especially if you can hinge the roof or a side for egg collection/cleaning
~ducks are not as prone to catching the diseased and parasites that chickens do, in part because they are in the water so much, but they all can get/carry many of the same things
~ducks tend to handle the cold better than chickens and don't mind the snow as much as chickens
~my ducks are more consistent daily layers in the summer than my chickens, but I think this varies with both duck and chicken breeds
~a male duck (called a drake) probably cannot safely be housed with your chickens
~my ducks and chickens all eat the same food, however my ducks eat more food in a day than my chickens, I am not sure if it is because the breed of ducks are larger than my chickens or because they lay larger eggs so they need more nutrition, probably a combo of the two
~my ducks go through more oyster shell and eggshells than my chickens, I think because they lay thicker shelled eggs they need more calcium than chickens
~my ducks go through much more water in a day than my chickens
~without electricity in winter I find the duck water stays thawed longer than the chicken water and needs to be changed less often, I attribute this to a few things, one is that they drink and play in water more often so they are constantly breaking the ice on top, also they dunk their whole head so they are stirring up the whole container, and the container is bigger so it takes longer to freeze
~most domestic ducks do not fly so it is easier to contain them with fencing, but it also makes them prone to predation
~my ducks are louder than my chickens
~maintenance of the duck run takes more time weekly than the chicken run and bedding gets changed more often and doesn't compost/break down as quickly as in the chicken run... probably depends how you manage things though. Filling/dumping/cleaning their pool takes some time too.