If some ink color runs low during a run you can get differences. The 82 Blackless cards can be found with black, no black and in between gray. In the 89 and 85 sets have all number of color variances in the team or name banners. I think colors may vary some series to series in a set. There are some legendary color difference backgrounds in the 52 set. Pick any card and search it closely for a month on eBay and my guess is you will find some differences somewhere
