Welcome back. The addition of Factory sets for those that have a noticeable difference between pack cards a nd the factory set is recent. A few are easier to tell than others. Some are listed as a parallel; others are listed as VAR to (almost) each card. Basically, if every card differed from each other, it was built as a parallel. But if there were some that were the same, they were listed as VAR. Admin's decision.
A few recent ones you will encounter -
1987 Donruss: listed as VAR because the DK cards are the same in both sets. The only difference in these is the orientation of the front to back. This is marked for each VAR.
1988 Donruss: listed as a parallel. This one has differences in the border color placements as well as the text on the back. Some are very easy to figure out the difference; others less so. Right now, there is no Note 2 field added describing the difference (I think eventually we may want to add this - my opinion only).
1991 Donruss: almost all of the cards were different in the Factory set, almost. I personally verified every card as I had a factory set intact. The difference is in the border colors. Many images have now been added but if there is no image, compare your card to the pack card. If it is a different border than what is pictured, then you have the factory set version. In this set, there is a second VAR on every card - "INC" & "INC." Because some collectors are obsessed in even a period or missing period, and this site serves all collectors, this VAR was added for all of the cards. So now this set has some 2100 or so cards listed.
This is just three of the most recent entries. It is a lot of work to list each one (ask vrooomed) but there are more to come.
Bruno
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Check my Profile page to see my 2023 Goals and my Lists of sets near completion (5 cards or less) or sets getting close (less than 100 cards missing and 75% complete).
https://www.tcdb.com/Forum.cfm/Page/B/ID/0/?MODE=VIEW&ThreadID=25745&C=0