It's easy to be confused.
ATCs have been active since the 1990s and were decreed to be for artist only to swap, face-to-face.
As it expanded they still were traded, but it stopped being face-to-face, but the term Art Trading Cards became common use. Together with magazine articles, books, and never ending products to aid in the creation of them. As well as classes and tv shows featuring them.
The beginnings of art cards go back centuries.
More information is available on website art-cards dot org.
You will see that many creators of ATCs stick rigidly to 'trade ONLY'. Especially if you do a search on the web.
When I started doing ACEOs, last April, I knew of them from ebay, but didn't understand, then I finally learnt about them on wetcanvas dot com, and knew nothing of trading. Once I realised what they were I joined in on ebay, and immediately was addicted - especially enamoured at their collectibility - they fit albums! I soon found out that there was much activity at the time trying to stop those selling them. I received many emails as well as not able to join ATC groups just because I sold (I did also trade a few at that time).
Theoretically this makes swapping of ATCs only open to those that make them, leaving many people who do not wish to create them, unable to collect them.
Fortunately ACEO creators have weathered this, as you can see by the large following on ebay.
ACEOs came about with the creation of a group of some visionary artists on ebay, suggested and headed by bone*diva, in October of 2004. The members put forth submissions to create a name other than ATC for use on ebay, and 'ACEO was the winning acronym by poll vote.
I still have a tendency to use 'ATC' from time to time because I do a lot of crafts locally, where the ATC name only is used. Mentioning ACEO is either still shunned, or unknown to so many who do create and collect art cards.
~Jillian
artist, Jillian Crider
... google me!