Both cards don't have words "debit" neither "credit" on them. I need to be really careful to use right one, as they are virtually indistinguishable. Yes, from m

Both cards don't have words "debit" neither "credit" on them. I need to be really careful to use right one, as they are virtually indistinguishable. Yes, from my point if view one is debit and one is credit, but I wonder is it possible to know what does payment system think about them? I dream about bank for geeks, where all technical information about each transaction could be seen in web interface :-)