Although manufacturers derive both from a single cassava plant, the process of producing cassava flour differs from that for producing tapioca flour. Cassava flour has a different makeup because of this. Cassava flour is much simpler and made from the whole, white part of the cassava root. The root is dried and finely ground to produce a finely textured gluten-free flour that you can use in many of the same products that might otherwise require wheat flour.
Tapioca starch is more highly processed as it consists only of the starch from the cassava root isolated from the rest of the root. The root is grated and washed to produce starchy water. That water is evaporated and the white residue that left behind is tapioca starch.
Because cassava flour contains the whole root, it has more fiber when compared to tapioca starch. Besides being beneficial for your health, fiber can also improve the texture of some baked goods by acting as a substitute for gluten. Cassava flour has a reputation for being the most similar to wheat flour of all the gluten-free flours.