Hatcheries do have the unfortunate habit of calling Easter Eggers Ameracaunas. It's distressing because it confuses people who are new to chickens to no end.
Ameracaunas were developed FROM easter eggers. They come in only 5 colors, and are very carefully bred. They are not available in hatcheries like EEs are.
Occasionally you can get a hatchery who keeps high quality stock, and can have an Easter Egger who looks very much like an Ameracauna (my hen is an example. To the untrained eye, she's almost identical to a silver Ameracauna). But more commonly they are all over the place with colors and features. Not at all standardized.