The core difference that I've noticed is that The Microsoft Data Warehouse Toolkit approaches the topic of building an end-to-end solution on top of the entire Microsoft BI Stack. However, the text only scratches the surface of "dimensional modeling" per se which is at the core of Kimball's methodology.

The Data Warehouse Toolkit: The Complete Guide to Dimesional Modeling on the other hand goes into great detail of how to structure a Kimball data warehouse design, and covers how to model "Business Processes" in depth. As stated by the reviewer, this book is database agnostic and, in my view, should be read prior to reading any other Kimball publication. In a nutshell, this is an absolute must read for any DW/BI professional.