Aggresion factor is equal to (Raise% + Bet%)/(Call%) which is essentially (Aggressiveness)/(Looseness). So, a loose player would need to be much more aggresive in order to have the same Aggresion factor as a tight one. If we assume that the guy with 65% VPIP plays much looser post-flop, he will be calling a lot post-flop, and then that is why he would also need to be more aggresive to get the same rating.