Rickybobby- Just the color of the casing. The guy who's link I posted seemed to change the price for some odd reason. Do a little googling and you'll find you can purchase this fixture anywhere from $120.00 to $179.00, as you have found.
Carey- I also have mostly non-dimmable units over my tank and have found that after months of acclimation, most every coral has gotten used to the intense light. I noticed that anemones and some LPS
need a much longer acclimation....perhaps many months is necessary.
Right now I have a LTA, green carpet, and 2 green BTA's in the back tank which are acclimating. I'm at 100% blue and about 60% white right now and they are doing fine.
Eventually, you will have your dimmable unit at full power, so I say, why spend the money on a dimmable unit when you can either raise it up a bit higher (temporarily) or perhaps cover some of the diodes with tape....
As for the colors v.s. blue and white models, I would suggest you look at both in person if possible and make your own decision about aesthetics. My main point about them is that you don't need the colors as far as I've seen. I have 1 species of montipora that has still had trouble coloring up under the straight blue and white units, but the other 10 montis are beautiful. Is this because of the colors? I don't think so.