Putting my micromanaging 'annoying as hell' pedant hat on for a moment.
While I believe this is meant to be the Executor Bridge tower it is clearly the generic ISD bridge tower coloured blue (I don't think the actually built a close up model Executor pod until ROTJ and didn't use it all the time even then).
The models show a difference in the way the bridge pod connects to it's extended tower on the Super Stardestroyer to the conventional connection seen in the shot.
I'm not sure how that can be made to work without building the bottom of the tower or making a matte (which would set back the project even longer).
Is it worth it for a barely noticeable difference????