There is a big difference between the two:
Investment bankers advise their clients on high level issues of financial organization. They manage the issuance of bonds, recommend and execute strategies for taking over and merging with other companies, and handle selling a company’s stock to the public.
A stock broker is a regulated professional broker who buys and sells shares and other securities through market makers or Agency Only Firms on behalf of investors. A broker may be employed by a brokerage firm.