Commercial banks are for profit and open to anyone who would like to use them. They are usually the largest depository institutions and offer many services, most of the time they offer more services than a credit union. Commercial banks are the better option for people who travel often and need multiple locations, and locations in different states.
Credit unions are not for profit, exempt from federal income tax, and are owned by members. These members must meet membership requirements; a common bond such as the same employer. They usually do not offer as many services as a commercial bank but are able to offer higher interest rates and charge lower fees.