What is the difference between FS and SDD?
Functional Specification (FS): The FS document captures the functional requirements of the system. This document outlines the system’s expected behavior from a business user’s perspective, capturing the purpose, inputs, and outputs of a process based on the ‘to-be’ processes outlined in the Business Process Design (BPD).
The FS document does not usually include detailed technical information about how the requirements will be implemented. Instead, it focuses on what the system should do to support the business processes. For example, an FS for a sales order process would outline the steps to create a sales order, the data fields required, any calculations or business rules that apply, the expected outputs, etc.
Solution Design Document (SDD): The SDD, on the other hand, takes the business process requirements from the FS and describes how the SAP S/4HANA system will be configured and customized to support these processes. This includes a detailed description of the system architecture, the various SAP modules that will be used, how they will be configured, and how they will interact with each other and with other systems.
The SDD focuses on the technical design of the system, capturing how the functional requirements will be met. Using the sales order process example, the SDD would detail how the sales order screen will be configured, any custom developments needed, how data will flow through the system, how the sales order process integrates with other processes like delivery and billing, etc.
In summary, the FS describes what the system should do from a business process perspective, while the SDD describes how the system will be designed and configured to meet these requirements. The FS is typically written by business analysts or functional consultants, while the SDD is typically written by solution architects or technical consultants.