Thrillers are built around tension, danger, and a constant sense of threat. Chases, conspiracies, crimes, mysteries, and limited time force characters to make decisions under pressure, while the plot usually moves quickly and unpredictably.
Unlike ordinary adventure, where exploration and discovery can be the central feeling, a thriller aims above all to keep the reader in suspense. Uncertainty and the expectation of the next threat are often more important than the scale of the adventure itself.