I water the duck poop right into the grass for fertilizer and we use the duck pond water on our garden. The duck poop is more liquid so it breaks down with water and it can be used directly on vegetation without burning it.
Chicken manure needs to be composted first or it will burn vegetation so it is harder to break down into usable fertilizer. I had some planter boxes that the chickens liked to perch on during the day and they killed a strip of grass where their butts hung over due to the poop being too hot and burning the grass, much like dog poop will kill grass.
We have started restricting the chickens to one area of the yard to keep their poop confined while the ducks can poop anywhere. The only times ducks leave noticeable piles of poop is when they are broody. Their normal poop just soaks into the ground and keeps the grass green.