I think this confusion can happen for any breed not just chickens. when people try to develop a new breed, it has to breed true and conform to specific standards. Some standards within a breed can be different like pattern and coloration. Breeding true means no matter how many generations you breed together they will keep the same expected color, pattern, and other breed standards. I think part of the problem with EE (I could be totally wrong this is just my take on it) is that it is not really a standard breed with standard colors it's just kind of a slap dash breeding of different breeds together to get some pretty egg colors.
Now take the brahma for instance it has 3 accepted standard colors light, dark, buff but people have bred partridge, laced, lavendar brahmas that will breed true but these colors and patterns haven't been recognized as an American standard (AMA?) for the brahma breed yet. But they are still brahmas. When you start mixing colors and patterns within a breed, chances are the results will not continue to breed true for the the second, third, fourth generations they'll continue producing different colors and patterns unless you have a specific plan laid out for their breeding. So just crossing a Dark brahma with a light brahma would be a mixed brahma or non-standard brahma, you should still get a brahma chicken with feathered legs, yellow skin, and pea comb. But the feather pattern and color won't breed true.
Take a brahma crossed with another breed like a leghorn that would be a mixed breed or hybrid. Because you may not get the feathered feet or size, and on the second and third generations you'll see the combs changing too. I'm sure there are experts who will probably skewer my post I'm just trying to put this in layman's terms.
Now take the brahma for instance it has 3 accepted standard colors light, dark, buff but people have bred partridge, laced, lavendar brahmas that will breed true but these colors and patterns haven't been recognized as an American standard (AMA?) for the brahma breed yet. But they are still brahmas. When you start mixing colors and patterns within a breed, chances are the results will not continue to breed true for the the second, third, fourth generations they'll continue producing different colors and patterns unless you have a specific plan laid out for their breeding. So just crossing a Dark brahma with a light brahma would be a mixed brahma or non-standard brahma, you should still get a brahma chicken with feathered legs, yellow skin, and pea comb. But the feather pattern and color won't breed true.
Take a brahma crossed with another breed like a leghorn that would be a mixed breed or hybrid. Because you may not get the feathered feet or size, and on the second and third generations you'll see the combs changing too. I'm sure there are experts who will probably skewer my post I'm just trying to put this in layman's terms.