Amex almost always pulls Equifax - they don't usually pull Experian, sometimes they do Transunion for some of the green charge cards.

And since your scores on those two both are high 600s - low 700s is a good enough score to get the amex easily.. A friend of mine got the DL amex with I think a 640 or 650ish score - I don't remeber the exact #. You'd be better off researching this at creditboards.com though.