Yes, I think the BoVD and our VDH (Villain Design Handbook) will cover mostly different territory.  Of course, I can't get any  news on exactly what's IN the BoVD, so I'm not 100% sure.
Here's what I posted on another related thread, just a few seconds ago.  It'll give you an idea of some of what's in the VDH.
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Of all the Kingdoms of Kalamar products, this one is the most "Kalamar-light" of any of them.  I'll do a brief chapter by chapter run through.
Villain Design Process - details the step-by-step process to creating a villain using the Villain Record Sheet, like the Player's Handbook details creating a character.
Introduction
 Chapter 1: Stereotypes and Beyond
This chapter begins by explaining what it means to be a villain.  it also provides suggestions for how to create villains using various combinations of races and classes.  It also details possible villain alignments and information on how to avoid obvious stereotypes.  You will also learn about variant game rules specifically related to villains, such as experience points, power levels, good-aligned and supernatural villains.  
Sections include:
   What is a Villain?
   Stereotypes
   Choosing Race and Class
   Villains and Alignment
   Experience
   Familiars
   Power Level
   Supernatural Villains
   Beyond This Book
Chapter 2: Archetypes
Lists the six primary villain archetypes and includes detailed examples and explanations of each.  Within each archetype, a range of subtypes are set out with personality profiles.  This chapter is rich with basic villain concepts useful in any DM's campaign.
Kalamar character backgrounds are written up as as examples of each.  Their stats are in Appendix A.  
Sections include:
   Deviants
   Devoted
   Fallen
   Inhuman
   Power Mad
   Visionary
Chapter 3: Inside the Mind of a Killer
Deals with the psychology of villains, their motivations and their obsessions.  Such details help the DM determine a particular villain's schemes and objectives as the plot thickens for the player characters.
Sections include:
   Thought Processes
   Motivations and Obsessions
   Goals, Schemes and Dreams of Darker Things
Chapter 4: Where Monsters Dwell
Setting the stage for a great adventure demands careful consideration.  This chapter discusses ideas for placing your villains and their lairs in cities, dungeons and wilderness areas.
Sections include:
   Setting
   The Urban Underground
   Pieces of the Urban Pie
   The Savage Wilderness
   Lairs and Strongholds
Chapter 5: The Head of the Serpent
This chapter describes the villain's place in secret societies and other organizations.  Here you will learn about villains who have an organization to back up their nefarious doings, and how the relationships within that organization affect the villain, as well as how they affect your PCs and your entire campaign.
Organizations from KoK are given as examples only.
Sections include:
   Independent Organizations
   Placement Within the Organization
   Building Levels of Intrigue
Chapter 6: New Villainous Rules
Obviously, these are just new rules for adding personality to your villainous characters.  Also included are details on usin gthese rules as player options.
Kalamar-specific mentions are rare.
Sections include:
   New Feats
      Enhanced Familiar Feats
      Metamagic Feats
   Variant: Anti-Feats
      Acquiring Anti-Feats
      Player Anti-Feats
   Variant Combat Maneuvers
Chapter 7: Prestige Classes
This chapter describes new prestige classes that are available to all characters, though they have certain qualities that make them particularly attractive to villains.  
The majority of these focus on independent organizations specific to the Kingdoms of Kalamar campaign setting.
Sections include:
   Villainous Prestige Classes
Chapter 8: New Spells
This chapter details new spells that you may make available to your villains of appropriate classes.  After your players get a taste of them, you  may feel free to make them available to player characters as well.
I'd say the only Kalamar-specific bits are the Basiran Dancer spells, and some mentions of characters and locations within the spell descriptions.
Sections include:
   New Basiran Dancer Spells
   New Bard Spells
   New Cleric Spells
   New Druid and Shaman Spells
   New Paladin Spells
   New Ranger Spells
   New Spellsinger, Sorceror and Wizard Spells
   Detailed Spell Listings
Chapter 9: Wicked Things
The items here are magical tools that a DM can use to arma villains, his lackeys or henchmen.  They often convey a useful benefit but are just as likely to come with some significant baggage.  As a DM, this is advantageous because it might make the PCs think twice about taking and keeping these spoils for their own use once they have defeated their nemesis.
Almost all of these items are Kalamar specific, though I have no doubt a DM with any ounce of talent could port them to other worlds.  
Magic circles and summonings is not Kalamar-specific, however.
Sections include:
   Magic Items
      Armor and Shields
      Weapons
      Potions
      Rings
      Rods
      Staves
      Wondrous Items
      Minor Artifacts
      Major Artifacts
   Magic Circle and Summoning
Chapter 10: Dangerous Denizens
This chapter discusses two new dungeon guardian-type creatures, and details several templates to add to your villains, including ghouls, mummies, skeletons, wights, wraiths and zombies.  There are details on how to perform the rituals leading to each template.
They do have Kalamaran names (the "self-willed greater mummy" translates as "kyseth," for example).  There are references to places on Tellene where such rites and rituals are found/were discovered.
Sections include:
   New Monsters
      Darkling Snatcher
      Guardian Effigy
   New Undead Templates
   Becoming Undead
Appendices
This is pretty straight-forward, so I won't bother to say anything other than that the adventure (a small encounter) is Kalamar-specific.
   Appendix A: Non-Player Characters
   Appendix B: Glossary of Terms
   Appendix C: Villain Record Sheet
   Appendix D: Adventure
      A Change in Plans
      NPCs (the soldiers)
      NPCs (the slaves)
Index
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Hope that clears up some of the confusion and gives you some idea what to expect.  
Mark Plemmons
Kenzer and Company
www.kenzerco.com