Here's the difference in a nutshell. A big hint/bit of info to always remember is that Araucanas look
NOTHING like Easter Eggers or Ameraucanas.
Hatcheries
do not, no matter their claim, sell purebred Ameraucanas or Araucanas as day old chicks.
Ameraucanas and Easter Eggers do look a lot alike at times because both are tailed, lay colored eggs, and have muffs/beard. But -
Ameraucanas ONLY have white soles on their feet, and ONLY have blue or black legs. They ONLY come in 8 recognized colors and if a bird looks just slightly different from the recognized color it is claimed to be, there's a very very good chance it is not that color nor an Ameraucana.
Most EE hens are brown and black or gray and red. Most EE roosters and red and black or white/yellow and black.
Araucanas seriously differ in
not having a tail,
not having beard/muffs, and instead about half the population of them out there have tufts. Tufts are
not beard/muffs, they are literal feathers instead of fluff that come out from each side of the face and curl up, down, back, or forwards. Some have only one tuft though, and many have none. Araucanas only come in 5 recognized colors but are allowed and in most cases come in many mixed, unrecognized colors. Araucanas though should ONLY have yellow soles on their feet, yellow skin, and green or yellow legs.
Does that help?
If not I have photos of all three, as I breed all three.