Text refers to the deeply textured look and feel of the paper. Not all text papers have textured surfaces. Smooth surfaces are also available. Uncoated book, also called offset, is available in a large number of forms. Many applications are cost constrained so it is generally used in lighter stocks compared to text papers.
Coated book is for the best reproductions where quality and color accuracy are important.
Coated book is made from a base sheet of uncoated book. One or both surfaces can have a coating. The coating is not always desirable. The coating keeps the ink from being absorbed by the underlying fibers. This is called holdout.