There are different kinds of prototypes, each serving different purposes. For example, the complexity of the technical function to be tested plays a role, as does the scope of the required prototype series.
The design prototype is used for practical verification of aesthetic and ergonomic aspects of industrial design or even product design. From a technical point of view, it is usually less functional.
The concept prototype is used to test partial technical solutions and partial functions.
A geometric prototype helps verify assembly and handling functions by providing a dimensionally accurate representation of the system. At the same time, the geometric prototype may have functional limitations due to prototype material and process.
The functional prototype is a prototype that represents most or even all of the functions of the actual technical system. Due to the systematically carried out selection of material and manufacturing process, it partly enables a pre-qualification.