A rim or mortice latch with a bevelled springbolt or roller bolt which shoots when the door is closed, but can be withdrawn by key from outside and by knob or lever handle from inside. Usually provided with a stop knob, slide or snib to hold the bolt retracted and to deadlock the bolt when shot in the closed position, even against the action of the key.
This is a latch, either mortice or rim type, which will secure the door closed. It can be withdrawn by key from the outside and by a knob or handle from the inside. It has a 'snib' to hold the latch back if required. This type of latch is not very secure and can be opened from the inside unless either deadlocked from the outside or using a locking handle on the inside.
A lock which automatically locks when the door is shut. Usually manually operated from inside and by a key from outside.