Trap: Used in the connection template to signify that the connecting world has a chaser that traps you in the current world. This means you should use Trap in the page of the world with the trap itself.
Catch: Used in the connection template to signify that getting caught by a chaser in the current world will lead to a trap in the connecting world. This means you should use Catch in the page of the world with the chaser.
Documentation (for the above template, sometimes hidden or invisible)