(Image removed from quote.)
How many differences can you spot?
Both the Hilton and Marriott are not built yet, though the Marriott's place is earmarked apparently. That's the most obvious difference to me.
As for a date estimate for the picture: I would estimate somewhere around 1989 or 1990. This guess comes from a few places, since I had a hard time finding the ending construction date for the convention center itself. First, I took a look at the cars on the road, the body styles line up with the ones I've seen in that general time frame. Then, I looked up the opening dates on the hotels. I couldn't find one easily for the Marriott, but the Hilton has it out there that they opened in 1992. Since the hotels are barely more than flat ground at this point (especially the Marriott), it's safe to infer it's after the convention center was done, but before the construction on the hotels started. A building of the size of the hotels can easily take a good year or so to build, so..
I'm glad to see if someone finds more than me though