Structured design and object-oriented design are two common approaches to design a system. Structured design is a method of breaking down a system into smaller and simpler modules, which can be independently created and tested. Structured design follows a top-down approach, where the system is divided into sub-systems, and then into modules, until the desired level of detail is reached. Structured design is suitable for systems that have well-defined inputs and outputs, and a clear hierarchy of functions. Object-oriented design is a method of modeling a system as a collection of objects, which have attributes and behaviors. Object-oriented design follows a bottom-up approach, where the system is built from reusable and interchangeable components, called classes. Object-oriented design is suitable for systems that have complex interactions, dynamic behavior, and multiple inheritance. Functional design and organizational design are not considered to design a system, but rather to describe the system's purpose and structure. Functional design is a process of defining the functions and processes that the system performs, and how they relate to each other. Functional design focuses on the what and why of the system, rather than the how. Organizational design is a process of defining the roles and responsibilities of the people and units involved in the system, and how they communicate and coordinate with each other. Organizational design focuses on the who and where of the system, rather than the how.Reference:Structured Design - an overview | ScienceDirect Topics,Object-Oriented Design - an overview | ScienceDirect Topics,Functional Design - an overview | ScienceDirect Topics, [Organizational Design - an overview | ScienceDirect Topics]