Ah. I see what you mean. This art is from the Novigrad chapter, but most of the art is abstract city vistas from above/street level. I'd assume they didn't have towns and cities planned out in any concrete detail when it came to layout, so at the stage of when the art is from, the work mostly seems to explore the style they wanted to do for various settlements in the game.
This doesn't quite match Oxenfurt, either. It is a closer match than with Novigrad for obvious reasons, but few of the works in the art-book match actual in-game locations to a significant extent.
How close is the artbook to the final game? I love artbooks and fromsoftware games but most of their art makes it fully into the game so there is hardly any differences between the concept art and final version. The Baldurs gate art book is incredible for that reason. A lot of the art is early in development and a lot of it changed significantly.
Depends on the chapter. Some stuff is clearly final. Like there isn't any art of Geralt or Ciri that isn't close to how they actually look in the game.
It's a free pdf download, if you have the game on GOG.