Just crunching numbers here: It look like the difference is half a tooth on the sprocket, but it is hard to tell exactly with real accuracy from a photo.
It would make sense, since a 360 degree circle divided by 18 teeth is 20 degrees per tooth. Since the crank turns twice for every turn of the cam, that means a difference of 20 degrees divided by two, or 10 degrees on a cam. The half-tooth difference (approximately) would be 5 degrees, so give or take a few minutes of a degree for error, it must be close to 4 degrees in actuality. So, by taking a late crank sprocket and moving one full tooth, you should get plus 5 degrees cam timing, which is probably not that good. Of course, to do this would mean you no longer have the aligning marks, so a crank dial would be the best way to get the exact amount... Perhaps it is only 4 degrees advance. I have looked into this before as a possible money-saving timing solution, but I don't think a 4 or 5 degree advance would be all that good, according to some I have heard from that tried it.
Mark