Black Book is just a collection of gear from the eBooks (plus the shadowtalk for that gear).
Eurowar Antiques has... Ummm... More to it than just gear and gear fluff. Not really sure how much more I can say due to NDA, but Black Book is as complete as it's going to get. It has all the gear, gear rules, and gear fluff that will be in Eurowar. It does not have the complete text of Eurowar though.
Bull