The three ideas
A trigger is the cue that starts the press — a backward pass, a poor touch, a certain player receiving. A trap is engineered: you deliberately leave one option open so the opponent plays into a space where you're ready to swarm. Tempo is the discipline of when to press and when to hold, because pressing costs energy and a team that presses everything presses nothing. The Athletic's piece walks through real examples of each; it's worth reading in full.
Why traps are the coaching level-up
Triggers get a team pressing together. Traps are the next level, because now you're not just reacting — you're inviting. Leaving the sideline pass open on purpose and jumping it is a team acting with a shared plan, and that only happens when players understand the why, not just the what. That's genuinely advanced, and I'd only layer it on once the basics of the trigger are automatic. But when a young team first springs a trap they set on purpose, they feel like a real team. That shared moment is worth a lot.