My duck eggs are more porcelain in texture, really smooth and usually almost translucent compared to chickens. Ive had all sizes and colors (usually in the blue range) but the surface is always smoother than a chicken.
Hope that helps.
I don't have a photo, but most of my Rouens lay off white eggs, not speckled, and larger than chicken eggs. About four such eggs are a full meal, two make a good hearty breakfast omelette. The yolks vary in color from orange to yellow.
One of my Rouen hens lays light blue-green eggs, they are slightly larger than the other Rouen eggs. These are the only eggs
I permit to hatch. I hope to eventually breed Rouens that dependably lay large blue-green eggs. Right now I have at least two
hens. The second hen is the first hen's daughter, and her eggs are not as large as her mother's.
The blue egg hen has a dark colored beak with no yellow on it. IDK if this is significant or not.
My birds are free range and really good layers, each hen laying about once daily from mid February into November- with more eggs laid in the spring.
I feed them cracked corn, poultry "layer" mix, and dry cat food. They are nuts for the cat food.
Rouen eggs make excellent fluffy omelettes, by the way.
That smaller brown egg looks like a chicken egg to me.
With three breeds of duck, all eggs are a pale beige color. Like happy flower's photo. Although some breeds do lay a different color. Cayugas lay black eggs.
When I had runners, the eggs were the same off white color; very pale beige.