Hi, I will try to tell you the idea I have about them however won't be able to give you further information because I haven't use that functionalities.
Continuity plan is used for customers who have subscriptions (for example a magazine) and every week, month, etc. they need to receive it. So the plan allows you to plan the purchase of the item to be ready for delivering the day they should receive it.
Sequencing is used for productions which need to be scheduled in a specific way instead of just by delivery date.
Hope it can clarify a bit the situation.
Look if you can find more information here: