I'd draw the line with high budget, team size, whether it's a first party title or not, graphics etc.
A Comparison Between Indie, AAA and AA Games | Gameopedia
Look at how Indie, AAA and AA games compare and stack up against each other on parameters ranging from budget to production values.www.gameopedia.com
The costs for these are extremely variable, lying between that of an indie and a AAA game.
There are not many concrete details available about AA game marketing budgets but they are between those of indie and AAA games, but usually a lot less than the latter.
Again, detailed data is not exactly available for AA games.
AA games fall in the middle
While data is not easily available for AA games, going by their budgets, their threshold lies between AAA and Indie Games.
so somewhere in the middle