The term prototype is often used in many different ways. People may describe an early version of the product as a prototype since it has many edges to be polished. However, these half-baked products do not fully recreate the final experience (since they are incomplete), require additional effort to build, and represent a bigger commitment to a specific direction.

A prototype is built specifically to test an idea, and their missing parts are a result of a conscious decision to prioritize those elements that are exposed to the user and are relevant for the design questions to get answered. A prototype fakes as much as possible, to the point that it is useless to reuse. That's not a problem since learning from it is the biggest value; after that, it can be disposed of.