The difference between a listed company and an unlisted company

There are companies that freely trade issued stock certificates on the stock exchange and companies that do not buy and sell issued stock certificates, but the former is called a listed company, and the latter is called an unlisted company.
The stock market has two roles
In the stock market,
A market for listed companies to issue new shares through the brokerage of securities companies (issuance market)
A market for freely buying and selling issued shares (secondary market)
There are 2 of them.
Stock investments are traded in this secondary market.