Here is the design of the kitchen, for some context. The hood extension is an add on and it’s not up yet. The crown that goes on the wall is 6 inches wide. Ceilings are 9 feet.

Your illustration has a cabinet style hood so obviously the crown would match the cabinet. Did you decide to do something different than this illustration? Maybe post photos of the area in question.

No, it looks like that only it has an extension above it to go to the ceiling. My husband thinks the wall crown just continued around that extension would look better instead of stopping the wall crown and then adding the cabinet crown.

So the cabinets are a foot short of the ceiling and you have built a box to hide the duct. Yes that is wall and gets wall crown

"Yes that is wall and gets wall crown"

I do not understand your instruction. The way this thread is written throughout is confusing. But I think the crown that is on the chimney hood extension should match the blue chimney hood extension. It would look jarring to have a white crown attached to a blue chimney hood extension.

You could also ditch the cabinet hood surround, and install a stainless steel hood with chimney. That solves the crown issue entirely. See first photo below.

Alternatively, you install a soffit or thick crown like in the second and third photos below. That solves two issues: (1) the continuation of the white crown (no blue crown would be needed), and (2) the fact that you have a one-foot empty space to the ceiling.

Yes, it would help if a drawing was provided that reflected the actual situation or even a photograph of the actual room. My interpretation of her reply was at the hood extension was trying to be nondescript, and she was trying to keep it looking as much like her original illustration as possible, which meant that everything blue ended a foot below the ceiling. Yes, if the face of the hood extends all the way to the ceiling, therefore, that section crown should be blue and should be cabinet crown.

I do not have a photo of the finished space because it’s not finished. I can post how it looks now but it’s not different than the rendition. You can see the unfinished crown off to the left.

Also the crown is not yet attached to the cabinets, obviously.

Are you extending a blue box to the ceiling flush with the hood? If so it gets blue cabinet crown. If you are installing a minimal wrap around the pipe that’s painted the wall color then it gets the house crown.