Yep, I think color is the main difference. I guess depending on what breeds went into making the sex-links (regardless of what color sex-link they make), would get you different temperaments, laying ability, and egg color.
How are their temperaments, in general? I know they have RIRs in their background, generally. The RIRs I have had were slightly on the "grumpy" side (compared to the silkies and Polish I've worked with otherwise). Do sex-links tend to share that trait or be more mellow?
I have BSL's that are Barred Rocks X RIR. I simply adore them and they have been awesome layers. Some of them will even jump up in my lap. In hindsight I would have went with the RSL's because it is so hot where I live and I am feeling bad for my black chickens in the heat.