Jevons and Marshall are both economists, as you know from Baidu. This sentence mainly means that their research methods are different. Jevons belongs to the kind of person who can't wait to show his discovery. Keynes said that he "spread ideas very quickly." Marshall wants to study things more thoroughly and know the ins and outs of things, so he doesn't need a "spotlight". This is almost two people's attitude towards marginal analysis. The concept of margin has existed in jevons for a long time, but it was Ma who applied this method to economic analysis.