Product invention refers to the creation of all kinds of unprecedented new products through human intellectual activities.
Method invention refers to the invention of steps or technical means to change one article or substance into another state or another article or substance.
Improved invention refers to the technical scheme that makes substantial innovation on the existing product invention or method invention. The difference between improved invention and product invention or method invention is that it is not a new product or method, but a substantial innovative technical scheme based on existing products or methods, which is a further improvement and improvement of existing inventions in technology.