Whats the Difference Between a Bank & a Credit Union
There are two main distinctions between a bank and a credit union. The primary difference between the two is in their business model, and how that business model translates to potentially a better deal for depositors. Credit unions are member-owned and so account holders are part owners of the institution. Also credit unions are not-for-profit, which often allows them to offer better fees and higher rates.
Like bank deposits,
money in credit unions is insured for at least $250,000 per account. Instead of
the Federal Deposit Insurance Corp., which insures bank deposits, the coverage
is provided by the National Credit Union Administration, but both agencies are
backed by the federal government. 
And you typically aren't restricted to using your own credit union's ATMs. Most credit unions offer either fee-free access to a network of ATMs or reimburse fees for use of other institutions' machines.