Of course, but they're a lot closer in skin tone than a lot of people think. The commenter didn't say there was no difference, just that it wasn't ... well, black and white.
Chris Rock is a comedian. He can be offensive sometimes. Doubtless he supports Obama. He supports Kamau Bell, another, more offensive comedian and got him a show on cable. But this is a comedy bit. People can laugh or not laugh depending on whether they think it's funny, but understand that it's not meant to be wholly serious. We can laugh at him if we can't laugh with him, but the knee-jerk "that's racist" response gets boring whoever says it.
FWIW: Romney Whiter than Obama was the subject of an article earlier in the year. A higher percentage of Mormons are non-White than Lutherans, Episcopalians, Unitarians, or members of Obama's own United Methodist Church are. Most of those non-White Mormons are Latino, rather than Black (or Asian) but it was still surprising to the guy who wrote the article.
Sorry, I should have said Obama was (nominally) UCC, rather than UMC. A higher percentage of Congregationalists are Black than Mormon, but because of the Hispanic Mormons, a higher percentage of Mormons are non-White than Congregationalists.