If you’re confused by the terms “alpha and beta prototypes”, don’t feel bad. Many people are in that boat with you. Also, the terms hold different connotations for different industries (software vs hardware, for instance). Because my field is medical device design, I’ll be talking about hardware prototypes here.
The product development process happens in stages. First you have an idea. Then you develop that idea into a concept (or several different concepts) of what your idea might look like as a product.
Once you have a concept that you think will work, you’ll set about turning it into a working model. Your working model might be an interim step to proving your concept’s feasibility (you might have to build several in order to work out kinks), or it could be your actual feasibility prototype. A feasibility prototype is intended to prove that your concept can be made into something that works generally as you intend. It gives you confidence that your idea is sound and should be able to be made using technology and components that are readily available (whether your idea is commercially viable is a different question).
Achieving a feasibility prototype is your first major milestone. The next milestone is the alpha prototype. Between feasibility and alpha prototype is where the bulk of the product development effort will be. You’ll look for standard parts that you can use in your design, and you’ll design custom components if you can’t find them stock. A lot of problem solving, testing and iteration will happen here. The goal is to construct a model/prototype of your product that uses the parts that will be in the product you eventually sell to consumers. This is the alpha prototype.
The important thing to understand is that the alpha is still an approximation of what your product will become. Now you’ll refine the design with the objective of getting it to its final form that will be manufactured and sold. The alpha prototype has gotten you close, but there will still be changes and refinements that will need to be made. You’ll probably find suppliers that can offer a similar component to the one you used for your alpha prototype but with a better volume discount for commercial quantities. You’ll want to incorporate those parts in the design, and test to make sure the new parts haven’t introduced any unintended consequences. You might also need to make refinements to specific areas of the design. You might find components that have better performance characteristics than the ones you were able to find for the alpha build.
The beta prototype will be built incorporating all of the final changes and refinements. The beta will be as close to the commercial product as possible. Why won’t it be the commercial product? Because it won’t have been built using the actual manufacturing methods and tools that commercial volume production requires. In most cases, beta prototypes will have been hand-built, one by one. They’ll be close enough to the commercial product that they can be put through final testing. If the beta prototypes pass any remaining testing requirements and perform reliably, you’ll be ready to transfer your design to manufacturing. The dream you started with five paragraphs ago will have become a reality.