Major vs minor interest

What exactly constitutes major and minor interest? Scouting? Shortlist? Report cards?

I only know that AI clubs that have 'major interest' are more likely to make an offer and pay over the odds for the player in question.

Yes major Interest may provoke a better chance of a bid but as to it being over the odds that is depending on circumstances.

As to the original question, i dont know for sure but its most probably to do with the club needing a player in that position so they have a bigger interest than someone who would just be buying the player for a squad rotation or backup basis.

A club would have more than one player on their Major interest list for the position needed to fill, so it all depends on circumstances who they eventually buy and how much they pay.