Explanation
One difference between the SAP Fiori launchpad and the classical SAP Graphical User Interface (SAP GUI) is that the SAP Fiori launchpad is role-based, while SAP GUI often offers single complex transactions for many user roles. This means that the SAP Fiori launchpad provides a user-friendly and personalized access to the applications and tasks that are relevant for a specific user role, while SAP GUI often requires users to navigate through menus and screens that are not relevant for their role. References: [SAP S/4HANA Sourcing and Procurement | SAP Learning], Course S4500, Unit 1, Lesson 1.

Explanation
You use an invoicing plan in this scenario. An invoicing plan is a method of creating invoicesautomatically at predefined intervals or dates without referring to any service entry sheets or goods receipts. You can use an invoicing plan for blanket purchase orders or contracts that have a fixed amount and validity period.
References: [SAP S/4HANA Sourcing and Procurement | SAP Learning], Course S4520, Unit 2, Lesson 1.

Explanation
Situation Handling is a feature that helps users deal with situations that require their attention or action. A situation template is a predefined configuration that defines the rules and actions for a specific type of situation. For the following business scenarios, a situation template exists in Situation Handling:
A supplier confirmation is pending, which means that a vendor has not confirmed a purchase order or has confirmed it with different conditions than expected.
A contract is ready as a source of supply, which means that a contract has been released and can be used as a valid source of supply for purchase requisitions or purchase orders. References: SAP S/4HANA Sourcing and Procurement | SAP Learning, Course S4520, Unit 8, Lesson 1.