Both books highly recommended as they complement each other. The atlas has a good image scale and plenty of stars and DSOs for a lifetime of navigating. The Deep Sky Field Guide is needed to know which objects are likely to be seen with any given telescope (provided you know it's limits).
I'm not sure which blurb you were referring to but full publisher detailed are here:
http://www.willbell.com/u2k/index.htm. (Click on maps for sample pages and hyper links for PDF extracts).
I have the three volume set with two volume atlas and one volume field guide. Willmann-Bell now sell the atlas as a single volume for the entire sky but the field guide is still labelled volume 3. I would think the chart numbers are the same in either type of set hence the same field guide. (Less weight in the field with the all sky edition because the introductory pages and all sky finder maps are not duplicated over two volumes I would think but I do not have the all sky version to be certain).
Enjoy!