Credit unions tend to be more conservative with initial accounts. They may hold your money for longer before giving it to you, at least until you've established a banking history. I tried opening an account with a local credit union in LA but, since it was the recession and since it was an entertainment industry credit union, they wanted to hold my money for five days. On the other hand, the credit union I signed up with in 2001, whose headquarters were in Anchorage, would give me access to my money within minutes. After all, I had 7 years banking history with them, including three accounts, a credit line one active and one completed car loan. The irony of credit unions is they're all on the same network... so to deposit checks in the Alaska credit union I went to the LA credit union, who would tell me that my money wouldn't be released for five days, so then I'd pull up my phone and show them that it had already been approved, flip them the finger and walk out. Long story short, Credit Unions offer you slightly better rates and service at the cost of conservative treatment initially... depending on the credit union. That said, both credit unions treated me with a lot more respect than Wells Fargo.
To add a little bit, credit unions often will offer very competitive rates on car and home loans, and many of them bump your account interest rate or dividend if you hold a loan with them. They are certainly more conservative with whom they lend to, but if you're in, they're hard to beat.