What's the difference between a bolt and a latch?

Different meanings and installation locations. The difference between a bolt and a latch:

1, with different meanings: a latch is a mechanical device of a door lock, which consists of a rotatable or pushing handle and a metal block fixed on the door. The door latch is a protruding metal rod that can slide between the door frame and the door leaf to lock the closed state of the door.

2. Different installation positions: the latch is generally installed at the bottom of the door and contacts the ground. The latch is usually installed between the door frame and the door leaf and can slide up and down.