Output B comes on at a specific set time after output A is turned on. When A is turned off, B also goes off.
A and B go on at the same time. B goes off after specific set time period, but A remains on.
Output B goes on for a specified time after output A is turned on. Output B will run for its specified time interval even if A is turned off during the B timing interval.
We may require that an output come on 7.5 seconds after system startup, remain on for 4.5 seconds, and then go off and stay off.
The interval would repeat only after the system is shut off and then turned back on.