Hatcheries are pretty consistent with with the type of EEs they turn out, but EEs bred in backyards can vary quite a bit.
Our EEs are the most docile & tame chickens we have (out of 7 different breeds). But..... I've heard black australorps are supposed to be calm & friendly and our BA were the most skittish chickens we've ever had - even worse than our 2 leghorns.
The hatcheries have chickens that they consider to be ameraucanas/americanas/araucanas and use these chickens to breed their stock from. Their easter eggers are not pure ameraucanas, but are still bred for certain traits. The hatchery EE's usually have muffs/beard, pea combs/ green or slate legs, and lay colored eggs. There are occasional exceptions, but there are also exceptions in other hatchery birds as well. I've purchased easter eggers 4 different times (for a total of about 34 EEs) from 2 different hatcheries and every single one of them had the above listed EE traits.
Private breeders may breed their ameraucanas with other breeds of chickens and come up with EEs and these EEs are not predictable in coloring, combs, beards, etc. They are not produced by breeding standard easter eggers (which hatcheries call ameraucanas, etc) with other easter eggers.