What is the difference between a credit card that I open directly at the bank versus one that I received by mail which I open in response to an invitation or preapproval?
There is no difference. Essentially, what you’re doing through the mail is the same as if you were to walk into a bank or credit union and open a credit card with them directly. You’re still filling out an application, they’re still pulling your credit reports and reviewing your credit scores, and they’re doing all of these things in both cases to determine whether or not you are qualified to have their credit card and what interest rate and terms they will apply to the account.