The World Is Not Enough Beta: King's Ransom This level probably has the most beta pictures and videos of any other.  At one time I think it was the opening level for the game. This is the main room of the MI6 Headquarters.  In the video that the beta picture on the left was taken from, Bond was coming out of the vault.  Now, the vault is one of the last places in the mission that you have to go.  Perhaps Bond was going to get the doctor.  The most obvious change is that the Ingalls Type 20 is no longer in the level.  There isn't a MI6 guard in this room anymore, and if you look at the back of the room, there isn't a directory on the wall either.
The left picture is a pretty early beta picture, as you can tell from the ammo gauge on the top right corner.  The building's directory in the wall has been changed significantly, but most importantly, the door on the right side is open.  I'm pretty sure that it is closed on all difficulties in the final version.
The picture on the left was one of the first pictures ever released for the game.  You can see that tow more doors have been added, and the floor is lit up from the red lights in the final version, and the ceiling is much darker.  The guards also have different outfits on.
 Not much change here.  The shadows on the floor are a little different, and the inside of the vault looks slightly different, but besides that, this hasn't changed that much at all.
This hasn't had that much change.  Even the rubble on the floor is the same.  The patterns on the wall are the same, the bends in the bars are the same, but the sparks coming from the ceiling, and the flames have both been added.  And Sir Robert King has been moved to the other side of the vault.
James Bond and another guy are teaming up against some guys coming at them from the elevator.  In the final version, those guys aren't there on Agent or Secret Agent.  That guard isn't there either.  That switch was added between the elevators, and that one door, all the way on the right of the picture, that you can hardly see, was all glass in the beta.  It makes sense, putting a door to the vault instead of glass.
This the the hall that has the security room in it on the upper floor.  The most obvious is that the KA57 isn't in the level anymore.  This is an older picture, but not that much has changed.  The hand scanner was added to the door, and so was the sign that says "Security:  Authorized personnel only."  But that's it.