ACEO or ATC ?

What is the difference between the two?  Years ago at an art show a friend of mine showed me some small works of art that she had created on 2.5 x 3.5 paper.  She explained that they were ATC's (Artist Trading Cards) and according to her, could not be sold, only traded or exchanged.  The idea was to encourage artists to share and collect the works of others.  While on ebay, I noticed the acronym ACEO and did not know what the difference was, since these little gems were also 2.5 x 3.5 inches.  I did a search on www.aceo.org  and have copied their description below.

 ACEOs are miniature pieces of art that measure 2-1/2" x 3-1/2". If a small piece of art has different measurements than this, it does not qualify as an ACEO.
The acronym "ACEO" stands for Art Cards, Editions and Originals. They can be original art, print editions or photographs.
The majority of ACEOs are two dimensional, but three dimensional elements may also be incorporated. Pop-ups, books, collages, and sculpture can all be ACEOs as long as they measure 2-1/2" x 3-1/2"!

ACEO history

ACEOs stemmed off of Artist Trading Cards (ATCs), an idea developed by the artist M.Vänçi Stirnemann. He based the size of ATCs on sports trading cards. ATCs can only be traded or given away. Their purpose is to share art and to encourage creative exchange between artists. Like ATCs, ACEOs may be made with any media, material, or method as long as they measure 2-1/2" x 3-1/2".
ACEOs are made with the intention to sell. The artist Lisa Luree started the ACEO group on eBay in part to make cards available to collectors.

So there you have it!  Personally I love both ideas.  As artists we are always searching for new ways to market our work and printing little ACEO gems seems like a good idea to me.  I think I may create a few originals too, just for the fun of it.  What a great way to start an art collection on a budget.  Just think, years from now you could have hundreds of little masterpieces from around the world, reflecting your own taste on what is beautiful and support the art community in the process!  Sounds like a win - win to me.