What's the difference between a patent and a scheme?

A patent is a specific patented technical scheme protected by law.

The scope of the scheme is larger, and many schemes cannot be patented.

Supplementary answer:

You can search patent literature by yourself, and the instructions record in detail the necessary technical contents of implementing the invention, including methods, raw materials, product effects, etc.

But the scheme is usually an idea, and the invented product cannot be directly obtained according to the scheme.