The red diablo chip is only programmable by diablo in Florida. They write the programs based on the parameters your dealer sends them. The black chip is for diablo dealers with a dyno that will write their own programs for you on the spot.
As for the difference in the chips, there is none. The chip is simply the final piece in the line that does the job of telling the computer what to do. SCT, Diablo, JET, whatever. What matters is the programming that is put on it. They both offer single and multi program chips. I know diablo has a computer "sleep" mode for anti-theft tactics. Don't know if SCT's chip has that or not.
Being as you have an 03, I wouldn't even use a chip though. SSince you can have a handheld flashing device, thats the route I'd take. There are several available. The two most debated around here are the new Edge tuner, and the SCT Xcal2. Then there are a few more, the SCT handheld (I think it was something like 1715), the diablosport predator, the hypertech handheld, and so forth.
Check all the threads about the Xcal2 and Edge here in the forums. THe others have respective websites to their names with tons of info.
Happy trails on that one though!