"Evangelical Dictionary of Theology" and "Evangelical Dictionary of Biblical Theology"

While both are published by Baker and both have Walter Elwell as editor, they are in fact quite different.    Each dictionary contains entries developed by different individuals and the two dictionaries often contain entries on a topic by different authors.   More than that, they each cover a different scope.  The Evangelical Dictionary of Theology is published by Baker Academic whereas the Evangelical Dictionary of Biblical Theology is published by Baker Book House, but is by no means an "entry level" dictionary.

For example:  The entry on "Angel of the Lord" in the Evangelical Dictionary of Biblical Theology is by Louis Goldberg and about 50% larger than the entry by T.E.McComiskey on the same topic in the Evangelical Dictionary of Theology (Second edition), yet the entry in the Evangelical Dictionary of Theology tends to be more scholarly and the entry in the Evangelical Dictionary of Biblical Theology more for the average church member intent on further study and learning.

In the Evangelical Dictionary of Biblical Theology, the entry following "Angel of the Lord" is about "Anger" (The Anger of God then Human Anger), then it moves to "Animals" (and God as their Creator and sustainer.), then to "Anoint", an entry again by Louis Goldberg. It then moves to "Anthropomorphism"

In contrast, the Evangelical Dictionary of Theology moves from "Angel of the Lord" to the "Anglican Communion", "Anglo-Catholicism" then "Annihilationism" before reaching "Anoint", an entry here by J. Van Engen (about 500% the size of that in the Biblical Theology volume) .  It then moves to "Anselm of Canterbury"

Given they come as parts of different collections, it is quite appropriate to try to get both dictionaries.

As to WHY two different dictionaries with similar but not identical titles, yet of apparently similar concepts but different scopes were compiled, I would have to leave that explanation to the Editor and to Baker.

The Evangelical Dictionary of Biblical Theology (which defines 500 terms and contributions from more than 125 evangelical Bible scholars)  is available from Logos seperatly for $40 http://www.logos.com/ebooks/details/evdictbt   (First edition 1997, file name evdictbt.lbxlls ).   It is (was?) also available as part of the Baker Digital Reference Library Level 3 collection (not currently available from Logos) (which was available in Logos 2 format and probably did not get updated to Libronix 3, although the individual book titles in the collection did - can still be added to your Logos collection if you can find an unused CD somewhere). http://www.libronix.com/page.aspx?id=partner98#BAKER 

The Second edition of the Evangelical Dictionary of Theology (1312 pages, published 2001, file name evdicttheo.lbxlls )  is available as part of the Baker Theology Collection (11 volumes) http://www.logos.com/products/details/4481 for $280

The cheapest way to get the EDBT is as part of the Baker Digital Reference Library Level 3 which can be found for as low as $9.99 and includes other reference titles as well.