The issue of direct versus indirect is an issue of whether there is an intermediate step or process involved. If there is no intermediate step, there is a direct effect. I there is an indirect effect; A effects B which in turn effects C. The issue of direct versus inverse is an issue of whether two variables move in the same direction or against each other. If A rises when B rises, there is a direct or positive relationship. If A falls when B rises, the is an inverse or negative relationship. It reminds me of right versus left and right versus wrong. Right versus left deals with direction and right versus wrong deals with morality.