There are several types of business structures including sole traders, partnerships, and public limited companies. Sole traders have unlimited liability for their business debts while partnerships share liability among partners. Public limited companies can sell shares on a stock exchange, must provide audited reports to shareholders, and limit owner liability to investment amounts. Commercial banking involves taking deposits, lending money, and other services while merchant banking focuses on raising funds, acting as intermediaries, and earning fees through services like bonds, stockbroking, and portfolio management.