I used to think that there were Araucana chickens--- the purebreds, who lay blue eggs, may be tailless and have tufts--- and there were crossbred chickens who laid blue eggs and which might be called Araucana, Americana, Ameraucana or Easter Eggers depending on the hatchery's whim.
Now, I had some 'Araucana/Americana' chickens from Murray McMurray hatchery some years ago and they were nice chickens. But the egg color was mostly disappointing, mostly greenish rather than blue.
Recently I was looking into hatching egg auctions on eBay and I found one for 'Ameraucana' chickens and the seller explained some stuff. There are actually two legitimate breeds of blue-egg chickens--- the Araucana, which is tailless and tufted, and the Ameraucana, which has muffs and beards. Both are developed from South American chickens. The Ameraucana in the US is very similar to the breed called 'Araucana' in Great Britain, more similar than the American Araucana is. In addition, genetic tests show the Ameraucana is related to various blue-egg chickens in Europe including the ones on the Shetland Islands. Since the reason I wanted Araucanas in the first place is because I couldn't get Shetland chickens, I decided to go for Ameraucana chickens and got two sets of hatching eggs from eBay.
I was very impressed by the blue color of many of the eggs I got, and hope that I have a good hatch to get started with the breed.
I believe that the crossbred chickens being sold as Araucana/Americana, Ameraucana and whatever ought to be labelled 'Easter Eggers' to avoid the confusion that has arisen. I'm not saying there is anything intrinsically wrong with the 'Easter Eggers'. It's just that they ought not be called by a name they aren't entitled to.
For more information on Ameraucana chickens, visit the Ameraucana Breeders Club.