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About a week ago I posed the question:  What is the difference between
Tapioca Starch and Tapioca Flour?  Here are the responses I've received:

Eleven people have always thought them to be the same thing, and their
baking turns out the same with one or the other.  Others had backup:
Michele called Ener-G Foods and was told they are the same; Steven Rice,
President of Authentic Foods, wrote, "There is no difference between
Tapioca flour or starch."  Karl Olsen & Cindy from NJ quoted Bette
Hagman from "The Gluten-free Gourmet": "Tapioca flour, sometimes called
tapioca starch, cassava flour or starch, is a very light, white, velvety
flour obtained from the cassava root imparting a bit of chew to baked
goods and is excellent used in small quantities with other flours for
most baking. It keeps well and can be bought in quantity."

Just when the question seemed settled, Connie in Ohio wrote in with an
interesting point, "Tapioca starch is similar to cornstarch and it is
used as a thickener.  Tapioca flour is what is used in making breads and
pastries.  The two are not interchangeable."  When asked how she knew
this information, she replied, "I have done an awful lot of reading on
the subject of gluten-free baking...I have also kitchen-tested literally
hundreds of dessert recipes and adaptations.  You see, I wrote a
gluten-free dessert cookbook that was endorsed by the Celiac Sprue
Association.  As a result, I have used both tapioca flour and tapioca
starch.  Oddly enough, tapioca flour (used in combination with other
flours) is a substitute for wheat flour; while tapioca starch is more
like a cornstarch.  But when it comes to potato products, the opposite
is true.  Potato Starch Flour is used (in combination with other flours)
to replace wheat flour; while "potato flour" is used like cornstarch as
a thickener.  Confusing, isn't it?"

Yes, it is confusing.  Who is right?  I have no idea and don't know if
this will ever be solved definitively.  Thanks to all those who sent
responses, but I must leave it up to the reader: you decide.
Good luck!
Tatiana