I think it means classical vs. hypermodern. Classical players seek to occupy the center with pawns (e.g. Queen's Gambit). Hypermodern players seek to attack their opponent's pawn center with pieces (e.g. King's Indian).
Both Anand and Carlsen are classical, not hypermodern players.
In numerous articles and videos, commentators often describe a game between current GMs (i.e., Carlsen vs Anand) as "classical game".
What exactly does this refer to?
Is it perhaps in terms of time control?
A particularly notable or defining game?