There are a lot of plants that are loosely considered "amazonica types". They are the shiny leaved types that look more like plastic or patent leather and have much thicker leaves than, say, an alocasia macrorhizza. Many people (and sellers) will lump any plant that looks like this into the group "amazonica", but, as far as I know (and I am certain someone will correct me if I am wrong) the only "real" Amazonica cross that is supposed to have "amazonica" in the name is Alocasia x amazonica "Polly".

Another common misabel is to call every one of these types "African Mask".

I recently saw an Alocasia guttata "Imperialis" labeled as "Alocasia African Mask".

Hi
I have an "Amazonica" that was purchased at Walmart so who knows?? lol. i find that you can change the intensity of the color by different culture methods. Those growing in
flowing water are about half as dark as those grown in full shade and dry. Those in standing water produce the largest leaves. What and how much feeding makes a big difference.
All the plants I have came from the Walmart start so i know they're all the same plant lol
When dealing with hybrids i know of no way to tell the difference. gary

From looking at a number of web sites there are many that strike me as similar to my "amazonica", though the others do have slightly differently shaped leaves, and perhaps even some color differences, and they are separate species, though I perhaps couldn't identify all with accuracy.