A production planning run in Advanced Planning (PP/DS) is a process that optimizes the supply and demand situation for a set of materials and locations within a given planning horizon. The possible results of a production planning run are:
Planned Order: A planned order is a proposal for internal production or external procurement of a material. A planned order can be converted into a production order or a purchase order, depending on the source of supply. A planned order can also be firmed, which means that it is not changed or deleted by subsequent planning runs.
Production Order: A production order is a document that defines the operations, materials, resources, and costs required to produce a material. A production order is created from a planned order or directly by the user. A production order can be released, confirmed, and settled as part of the production process. Reference: [SAP S/4HANA Production Planning and Manufacturing Certification Guide], page 181; [SAP Help Portal: Production Planning Run].

Dependent requirements are the requirements for components that are derived from the requirements for the finished product or assembly. They are created when an independent requirement is created for the finished product or assembly, such as a planned independent requirement, a sales order, or a stock transport order. They are also created on assembly level during the planning run, when the system explodes the bill of material (BOM) of the finished product or assembly and calculates the requirements for the components based on the BOM structure and quantity. Dependent requirements can be created for multilevel or single-level BOM structures, depending on the planning strategy and the BOM explosion level. Reference: Dependent Requirements | SAP Help Portal, Material Requirements Planning (PP-MRP) | SAP Help Portal.

A production version is a combination of a BOM and a routing that defines how a material is produced. For a production version to be valid and consistent, the following requirements must be fulfilled:
The deletion flag must NOT be set for the BOM or the routing. The deletion flag indicates that the BOM or the routing is no longer used and should be archived. If the deletion flag is set, the production version cannot be used for production planning or execution.
The lot size range must be within the lot size range of the assigned routing. The lot size range specifies the minimum and maximum order quantity for which the production version is valid. The lot size range of the production version must match or be smaller than the lot size range of the routing, otherwise the system will not find a suitable routing for the production order.
The assigned routing and BOM must be valid in the entire validity period. The validity period defines the time frame for which the production version is valid. The validity period of the production version must be within or equal to the validity periods of the routing and the BOM, otherwise the system will not find a consistent BOM and routing combination for the production order. Reference: [SAP S/4HANA Production Planning and Manufacturing Certification Guide], page 113; [SAP Help Portal: Production Version].

The material type is a key attribute that classifies materials according to their characteristics and determines how they are processed in the system. The material type influences the following aspects of material management:
Which material master screens appear and in which sequence: The material type controls which fields are required, optional, or hidden in the material master record. It also determines the order in which the screens are displayed when creating or changing a material master record. Different material types may have different views and fields depending on the business requirements. For example, a raw material may have a purchasing view, while a finished product may have a sales view.
Whether the material is produced in-house, procured externally, or both: The material type defines the procurement type of the material, which indicates how the material is procured. The procurement type can be in-house production, external procurement, or both. The procurement type affects the planning and execution of the material requirements. For example, a material with in-house production procurement type will generate planned orders, while a material with external procurement type will generate purchase requisitions or schedule lines.
The material type does not influence the following aspects of material management:
Which document types and class categories are allowed: The document type is a key attribute that classifies documents according to their business purpose and determines how they are processed in the system. The document type controls the number range, field selection, and status profile of the document. The document type is independent of the material type and can be used for any material type. For example, a purchase order document type can be used for any material type that is procured externally. The class category is a key attribute that classifies classes according to their application area and determines how they are processed in the system. The class category controls the characteristics, object types, and inheritance rules of the class. The class category is independent of the material type and can be used for any material type. For example, a material class category can be used for any material type that has characteristics.
Which plant-specific and plant-independent statuses are allowed: The status is an attribute that indicates the current condition of an object in the system. The status can be plant-specific or plant-independent, depending on whether it applies to a specific plant or to all plants. The status is independent of the material type and can be used for any material type. For example, a material can have a plant-specific status of blocked for quality reasons, or a plant-independent status of discontinued. Reference: Material Type | SAP Help Portal, Material Master (LO-MD-MM) | SAP Help Portal, Document Types | SAP Help Portal, [Class Category | SAP Help Portal], [Status Management | SAP Help Portal]

A phantom assembly is a material that is not physically produced, but its components are directly consumed in the production of a higher-level material. To set up a material as a phantom assembly, you need to do the following steps:
Define the special procurement type as 50 (phantom assembly) in the material master of the phantom assembly. This indicates that the material is not procured or produced, but its components are exploded in the BOM of the higher-level material.
Change the item category of the phantom assembly in the BOM of the higher-level material to N (phantom item). This indicates that the phantom assembly is not relevant for production order or MRP, but its components are.
Alternatively, you can change the phantom item indicator for the phantom assembly in the BOM of the higher-level material to X (phantom assembly). This has the same effect as changing the item category to N, but it also allows you to use the same BOM for different purposes, such as costing or sales. Reference: [SAP S/4HANA Production Planning and Manufacturing Certification Guide], page 68; [SAP Help Portal: Phantom Assembly].

The work center that represents the production line for repetitive manufacturing is maintained in two places: the repetitive manufacturing profile and the production version. The repetitive manufacturing profile is a control parameter that defines the basic settings for repetitive manufacturing, such as the planning type, the backflushing method, the confirmation type, and the production line determination. The production version is a combination of a bill of material (BOM) and a routing or a rate routing that specifies how a material is produced. The production version also contains the work center that represents the production line for the material. The production version is assigned to the material master and is used in the planning and execution of repetitive manufacturing. Reference: Repetitive Manufacturing Profile | SAP Help Portal, Production Version | SAP Help Portal, Make-to-Stock Repetitive Manufacturing | SAP Help Portal.

The difference between co-products and by-products is mainly in how they are accounted for in the production process. Co-products are products that have a relatively high sales value and are produced simultaneously from the same production process. By-products are products that have a relatively low sales value and are produced as a side effect of the main product. The following points explain the difference between them:
Only co-products are identified by a special item category in the bill of material (BOM). This item category is L (Co-product) and it indicates that the component is a co-product that shares the joint costs of the production process with the main product and other co-products. By-products do not have a special item category in the BOM. They are usually entered with a negative quantity and a negative item category, such as N (By-product)12.
Only co-products can be manufactured in isolation from the main product. This means that co-products can be produced independently from the main product if there is a demand for them. By-products cannot be manufactured in isolation from the main product. They are always produced as a result of the main product3 .
Only co-products have a zero inventory valuation. This means that co-products do not have a price in the material master and their inventory value is calculated based on the apportionment of the joint costs of the production process. By-products have a fixed inventory valuation based on the price specified by the price control in the material master. Their inventory value does not depend on the production process12.
Only co-products appear in the process or production order settlement rule. This means that co-products are settled to different receivers, such as sales orders, cost centers, or profitability segments, based on the apportionment structure defined in the material master of the leading co-product. By-products do not appear in the settlement rule. They are credited to the production order and reduce the total costs of the process12.
Reference:
1: SAP Help Portal: Co- and By-Products
2: SAP S/4HANA Production Planning and Manufacturing Certification Guide, Chapter 8: Product Compliance
3: SAP Co-Products and By-Products Tutorial – Free SAP PP Training – ERProof3
4: Co-Product and By-product in Production order | SAP Blogs2

The duration of an operation for production is determined by the combination of data maintained in the routing and the work center. The routing defines the sequence of operations, the work centers, and the standard values for each operation, such as setup time, processing time, and teardown time. The work center defines the capacity, the formulas, and the scheduling parameters for each operation, such as base quantity, operation rate, and queue time. The system calculates the duration of an operation by multiplying the standard values from the routing by the factors from the work center formulas and adding the scheduling parameters from the work center. For example, if the routing specifies a processing time of 10 minutes per unit and the work center formula is processing time = (processing time / base quantity) * operation quantity, and the base quantity is 100 units, then the duration of the operation for 50 units is (10 / 100) * 50 = 5 minutes.
The bill of material (BOM) (C) and the material master (D) are not data objects that determine the duration of an operation for production. The BOM defines the components and the quantities that are required for producing a material. The material master defines the general and specific attributes of a material, such as the material type, the unit of measure, the MRP data, and the production data. These data objects are relevant for planning the material requirements and the production costs, but not the operation duration. Reference:
https://help.sap.com/docs/SAP_S4HANA_ON-PREMISE/c00ad2cac7be4ef29a4461ba114e4f91/051ebf53d25ab64ce10000000a174cb4.html
https://learning.sap.com/learning-journeys/manage-production-orders-in-sap-s-4hana-manufacturing/scheduling-production-orders_cc390d5f-b87c-4c4d-9472-8bb10ea4f476