I have just had a look at the content lists for these two books on
fatbrain and they have almost identical

The Ruby Way
http://www1.fatbrain.com/asp/BookInfo/BookInfo.asp?theisbn=0672320835&mtype=St

Introduction
Day 1. Getting Started with Ruby Why Ruby?
Day 2. Hello, Objects!
Day 3. Containers.
Day 4. Iteration and Flow Control.
Day 5. The Characteristics of Objects.
Day 6. Ins and Outs.
Day 7. Catching up on Details.
Day 8. Pattern Matching.
Day 9. Inheritance and Modules.
Day 10. Program file Layout and Design.
Day 11. Modules and Classes in Depth.
Day 12. An Introduction to Recursion.
Day 13. Mastering the Operating System.
Day 14. Arguments, Blocks 'n procs.
Day 15. Toward Habitable Interfaces Interface Size and Intuitiveness.
Initialization. Providing Iterators. Doing the Math. Default Values.
Using Argument Types.
Day 16. Putting It Together (part 1).
Day 17. Tk.
Day 18. Gtk
Day 19. Some "advanced" Features (that aren't so hard).
Day 20. Working with the WEB.
Day 21. Putting It Together (part 2).
Appendices.

Teach Yourself Ruby in 21 days.
http://www1.fatbrain.com/asp/BookInfo/BookInfo.asp?theisbn=0672322528&mtype=St

[See above]

TRW has more information in the table of contents but TYRi21d has
identical chapter headings.

What is going on?