The differences include: being able to withdraw from your e-savings account at citibank without penalty, citibank never charges the extra ATM fee (the ATM's bank will though), and citibank has better reviews on costumer service.
Hi. Yes, BOA will cash any BOA check, provided the account is valid, there are sufficient funds in the account and you have proper ID.
If you have no account with them, usually 2 forms of ID are...