I haven’t read this book, but from the blurb and reviews on Amazon, it seems to focus on why the Catholic and protestant Old Testaments are not the same.
And the reason for this is really quite simple. When the early Christians compiled the Canon of Scripture, they simply adopted whatever OT Canon was in use by the Synagogue down the street. There was (and still is) no “official” Jewish Canon, and there were regional differences even in Apostolic times, which is why the Catholic OT differs slightly from some Eastern OTs - everybody used whatever was in use by the Synagogue down the street. While many protestants initially accepted the same OT as the Catholic Church, they gradually took the same approach that the Catholic Church took fifteen centuries earlier, accepting whatever was in use by Synagogue down the street. But, by the Sixteenth Century, the OT books which were originally written in Greek had been gradually excluded from most Jewish texts (such as the very influential (and almost “official”) Masoretic Text (compiled between the Seventh and Tenth Century).
Of course, Catholics had no problem with the OT Canon used in the time of Jesus, including the portions written in Greek. After all, almost all of the New Testament was written in Greek (Matthew was originally written in Aramaic, but none of this oritinal text survives).
Dr. Bruce’s book focuses on the canon of the New Testament, practically ignoring the Old testament, so I believe the books are VERY different.