Chuck,

You can see the differences in all the designs at:

http://www.chipguide.com/cgi-bin/search/search.cgi?id=wibons

I don't remember why, but they pulled the old set back in 1997 and replaced them with the new one. In your photo, the one with the green denomonation is the new style. Apparently they have moved some of the old ones back into play now.

Greg