how is a credit union different from a bank?

A credit union is a member-owned, nonprofit organization. By law, credit unions must not earn a profit at the end of the year. The credit union reinvests its earnings to enhance services, provide the best rates, or return the earnings to the members in the form of a dividend. There are no hidden fees and operating costs are kept to a minimum. Credit unions exist to serve their membership.

Banks are for-profit businesses, with the overhead and expenses associated with running a company.

You do business with a bank; you own your credit union.