General Motors can represent the world's leading automobile company - General Motors (GM); it can also represent General Electrics (GE), a diversified service company in the United States.

General Aviation refers to the use of civil aircraft to engage in civil aviation activities other than public air transport, including operational flights in industry, agriculture, forestry, fishery and construction, as well as medical and health care, and emergency rescue Flight activities in disaster relief, meteorological detection, ocean monitoring, scientific experiments, education and training, culture and sports, etc.

So don’t get confused. “GM” in General Motors is the translation of the company name. It is a brand and a noun. The "general" in general aviation is not a noun, but an adjective.

Do you understand now?