Understanding the fundamental differences between these two styles of play will help you find the right game for your taste.

Both genres share a common ancestry, tracing their roots back to custom map modifications in classic RTS titles.
The Classic Tower Defense
Traditional defense games are almost exclusively single-player experiences focused on surviving against AI-controlled hordes.

The challenge comes from optimizing your maze of turrets and managing upgrades as the waves become progressively harder.
Almost always single-player.You only place buildings.Pacing is generally slow and methodical. The Modern Tower Rush
Instead of just defending, players must simultaneously manage an offensive assault against a human opponent’s base.

The pacing is incredibly fast, usually locking players into a strict three to five-minute time limit per match.
FeatureDefense GenreTower RushCore ObjectiveSurvive all waves without losing livesWin the PvP duelPlayer ActionManaging trapsManaging a deck of cards Which Should You Play?
If you crave adrenaline, competitive ladder climbing, and testing your wits against real humans, the modern arena is for you.

The evolution from static defense to dynamic rushing proves that strategy games are constantly reinventing themselves.