Hey Leondias,

There are color variations - some people thing that they are due to process variations, i.e. different die batches, etc...

Besides the color differences, I know of three. The image (and link below

http://www.thechipboard.com/cgi-bin/tcb/archive6.pl?read=69085

to an archive post) shows the three variations that I am aware of - above and beyond the color variations...

I hope this helps

Dick