As can be seen on the cards below, the print runs can be tracked by where they were printed - Italy or Japan. Each print run also has a letter to denote the print run - I've seen A, B, C, D and none noted (I call it blank). For blank I will use the code
The following card had no differences in the print runs other than the date listed and the print run letter shown on the back. Some wouldn't find that to be enough of a variation that would warrant collecting it.
The type of change show above was common in cards that discussed sports in general terms and in cards of people who were no longer active in sports. I plan to collect those as variations.
Some cards, like the ones shown below, have updated statistics that reflect the long-term release of each print run.
I like that they took the time to update the winners of certain events. They didn't do this with every individual, but they did a good job with events.