The J-curve is basically a J shaped diagram or graph that portrays an initial fall and then a rise more than the starting point.l It is normally used in economics, where it portrays the trade balance of a country following a devaluation.
On the other hand, the S-Curve is basically the logistic curve. The diagram or graph is portrayed as an initial stage of growth which is exponential. As saturation begins, the growth slows and the at maturity level, the growth stops.