All three are entirely different. Each one started as a contest (held at different times) in Knitter's magazine where knitters from across the country designed and submitted their square. The best of the best won prizes and the top 24 squares from each contest were published in the magazine. Eventually the patterns were published in the 3 different books.
I'll just say that the Great American Aran Afghan remains as one of my all time favorite knitting projects.
