What's the difference between "northern r&b soul and southern r&b soul music?

I thought that rhythmn and blues was the same for both the northern and the southern United States. Apparently there is a difference with the music recorded by different artists. Question: in your opinion, what are some of the songs, that have been recorded, that actually reflects either the north or the south r&b music? Would Chuck Berry be a good example? Where would he fit into the north vs. the south r&b music?