What's the difference between deployment policy timing and automated task timing?

I don't fully understand the difference between an automated task and the deployment policy as for what the timings means in both. One can specify days and hours when the task or policy should trigger its activity.

Let's say I want to schedule updates on Monday and Tuesday (Patch Tuesday occurred and next Monday these updates will be installed after having been approved) between 12h30 and 15h30, trigger a notification when they are going to be installed on the user's device and ask them for a reboot if needed afterwards. If that reboot request is skipped, it will be forced the next day.

In this case, will i need to set both days and the time range 12h30 -15h30 in both the task and the policy or how does this work in the described case? And what if I want the updates to even be installed on other days if the device wasn't online on Monday and Tuesday?