Ornamental ducks differ from domestic ducks in several ways. The biggest differences are in breeding habits and in temperament.
Unlike domestic ducks most ornamentals only nest at one time of year, for most species this is Spring. Domestic ducks may also lay the majority of their eggs in the Spring, but will also lay sporadically through Summer, Fall and sometimes even though Winter thus producing many more eggs in a year than the ornamental duck, which may only produce a handful of offspring in a year. To reproduce often domestic ducks require little more than food to eat water to drink and some nesting material. Ornamental ducks are much much more picky, if their habitat is not to to their liking they will not reproduce.
Domestic ducks can be kept in small groups, one drake with several hens, and still produce a good percentage of fertile eggs. For most ornamentals it is recommended to keep them in pairs, as the drake will usually only mate with one female at a time. You may have some success keeping a few species in trios as some drakes may take a second mate after his first choice has begun to set her nest. However this can be risky because if the bird that is his second choice begins to lay first, the second choice hen may produce all infertile eggs.
Most domestic ducklings are easy to raise, and will begin eating without any special care. Many ornamental species are more delicate and can be difficult to raise from ducklings in particular it can be hard to get them to eat.
Domestic ducks usually will stay around pretty well if kept on one water and left fullwinged. Ornamental ducks almost always will fly away and not return if given the chance. If you want to keep ornamental ducks free range we recommend purchasing pinioned birds (permanently flightless).
Domestic ducks such as calls are often shown and make great 4-H projects for kids. In my opinion the typical ornamental duck is to nervous for the show environment and would not do well there. Also to my knowledge their are no standards for wood ducks, mandarins or other wild birds.
Domestic ducks are often kept as pets, and can become very tame, they may learn to follow you around, eat from your hand, maybe even climb into your lap, these are not behaviors that should be expected of ornamental ducks. Ornamentals, even though they may be many generations removed from the wild, still retain many of their wild instincts. They can become accustomed to you, and may learn to act naturally in your presence, but most will never like to be handled, or even pursued in any way. Excessive handling can actually be harmful to the health of ornamental birds. We never catch or handle any of our birds unless it is absolutely necessary.
It is especially important for the beginner to understand that ornamental ducks do not typically behave like domestic ducks such as calls or mallards. Ornamentals are much more nervous and often stress out easily thus they may not be able to live in the same conditions that have worked well for you with domestic ducks.