They have to do with unit size - I think.
Someone had a similar question a few weeks ago about Grande Vista and I called the resort. The front desk person did not know the answer and I was transfered to someone else. I was told that the designation pertains to room size and not a specific building. This may be different for a resort that has ocean front and ocean view rooms, these rooms may have their own codes.
For what it's worth, my Grande Vista three bedroom shows up as three different units when I look at it on II. The three bedroom has one code, and the two bedroom and efficiency sections have their own code. I would call II if I was curious.
Charles
