I’ve worked in the egg industry, sorting eggs coming out of the stables and checking on the hens. Thanks to that workplace, I’ve been around where both white and brown eggs were laid, and I can tell you that there is indeed a difference, even though it’s not one that a regular consumer will ever notice.

The difference is that breeds that lay white eggs are more productive than those who lay brown ones. Maybe not as far as weight goes, since brown eggs tend to be slightly heavier with thicker shells, but when it comes to the number of eggs produced in a day, there is.

Slightly heavier eggs on average is not a good thing according to the industry, since they can’t sell those that are too big as grade-A to restaurants or supermarkets. Instead they end up at bakeries or factories at a discount.

Then again, thanks to their thicker shells, brown eggs are a lot less likely to come out of the stable cracked, so less likely to have to be discarded, and thus keeping those breeds is often seen as worth it for egg producers nevertheless. This is also why in some markets, brown eggs cost more or are even the default.

That said, where I live, there is no difference in price between white and brown eggs, it’s just rarer to see brown ones in the supermarket.

I should say that the place I worked at was a small-scale operation with about 2000 hens of each breed. And even that wasn’t enough for it to remain profitable.

So, if you want to only consume eggs that come from truly happy chickens, you have to find someone with a flock of 10–20 who’s OK with selling (or giving) some of their surplus to you. And you have to be prepared to go without all through winter.