I wouldn't say EXACTLY the same. Cat, Case and the like that used to rebadge a SO ratcheting screwdriver now are rebadging the williams version. Differences are the knurling on the shaft, texturing on the direction control collar and the SO handle is square where as the williams version is more like a reuleaux triangle in cross section.
Here is a side by side to help illustrate.
http://www.garagejournal.com/forum/showthread.php?t=184529
I'm not sure when but I think it was fairly recently that Cat and the like changed to the more williams version. I recently picked up a few of the old style Cat branded ones and they are exactly the same as the SO version with Cat instead of Snap On lettering. Square handle, knurling and all.