Minor Revisions: Like revisions of the games' codes, the other items that came with the game could have been revised. It could be the manual, the spine card, the regcard, the CD label or any other items. We call these updates "Minor Revisions" to avoid any confusion with updates of the codes commonly called "Revisions".

Alt. Versions: Some items that came with the game have been modified or have been deleted when the game has been reprinted, so different versions exist. This is what we called "Alt. Versions" here.
"Alt. Versions" could also stand for some games that came with goodies (trading card(s), picture on the internal cover, photo, etc.) which are sometimes differents from one copy to another.