Difference Between Planned & Prod. Orders in PP

When user should opt for planned order instead of production order? I have high level knowledge that planned order is meant for REP. industry. Any other major parameters to be consider for Discrete, as both allow material kitting & backflush based on order number?

Planned orders are results of running MRP. Shortages of materials that are set to internal procurement will create planned orders, which can be converted into production orders. Production orders are like "hard copies", they cannot be adjusted by MRP anymore. Well that's for a discrete environment, not sure about repetitive manufacturing.

One we firm the planned order changes will be not reflected in the subsequent MRP, correct. e.g. BOM change. New components will not be recommended for firm planned order.

I'm assuming when you ask about when to use planned vs production orders you are asking when to use Repetitive Mfg (with PE planned orders) vs Discrete Mfg (with production orders). We use both and while we're not perfect in our approach yet we are gaining a better appreciation for the two.

For repetitive, the planning is much simpler, you basically run MRP against your demand and you get planned orders. You can change and firm these manually or you can use time fence strategies, and you can have multiple operations running through multiple work centres. They are very simple to maintain and use. Repetitive is normally run against shorter lead time build, where we don't need a high level of control. If we have the option we go with Repetitive.

Where we want a better level of control we go with discrete. Planned (LA) orders are created from a run of MRP against your demand. These are converted to production orders, released, and processed. There is a lot more control (and work) with this order type than we see with Repetitive planned orders. We can link documents to the order, we can change the routing and the BOM on the order, and we have better visibility of the individual orders while they are in manufacturing. Costing is against the order as opposed to Repetitive where the costs (and variances) are seen against the cost collector. After everything is complete, you still have a record against the build. The order stays intact, though it may be complete and closed, you still the retain history.