Just to seem totally ignorant ...what is the difference? I'm a newbie ! can you tell? It shows , doesn't it !
Easter Eggers are mutt chickens that carry the blue egg gene. They usually have Ameraucana blood in them mixed with something else. Because they are mutts, they can have almost any coloration, although that vaguely-duckwing pattern that those birds are showing is extremely common. They are very common, and what many people order as "Ameraucanas" from hatcheries or buy from feed stores. They most commonly lay green eggs, but can also lay blue or brown (the brown is quite rare, as long as the bird has a pea comb).
True Ameraucanas are much less common, and are a purebred breed that only has a few accepted colors--none of which is that duckwing-like pattern. Unfortunately, because hatcheries sell their EEs as Ameraucanas, many people mistakenly believe that they have a rare breed when it's not true, and they then sell their EEs as Ameraucanas and perpetuate the cycle of misinformation.
However, that does not mean that these birds for sale aren't worth buying because they are mutts! I have both EEs and Ameraucanas, and my EEs lay more, prettier colored, and larger eggs. While I love the look of my Ameraucanas, I love the fact that no two EEs look the same or lay the same color egg. If the price were right, I'd buy that group in the photo. They look like nice birds.
BTW--A Newbie is just a BYCer we haven't known very long yet. It's a steep learning curve, but soon you won't feel so new any more. And you'll stop feeling so new the way most of us did--by asking questions and building your knowledge. And then you'll be able to "give back" that knowledge to next years' newbies! Welcome to BYC!