Have you ever wondered if brown eggs are better than white ones?
Actually, there is no difference at all!

The different color of the shell depends only on the breed of the hen that produced them.

The white hens, like the most common Leghorn, lay white eggs, the reddish ones, like  Rhode Island Red ones, lay brown eggs. 
The appearance is different but their quality and nutrition values are exactly the same!

What does their size depend on?
It has nothing to do with the physical size of the hens as you might think, but their age. 
The older hens produce larger eggs. 
Often the first eggs of younger hens, at the beginning of their reproductive process, might be smaller.