Actually there is no difference when you pay via apps(Alipay, Wechat etc) or via eCNY from customer point of view. You pay same amount. The difference is on the merchant side.China's central bank digital currency (CBDC) has showed up at the first China International Consumer Products Expo in south China's Haikou port city, giving foreigners at the event a taste of the payment experience it offers.
All those payment apps are middlemen and will take a bite of the payment. The eCNY eliminate this third party settlement. Therefore saving settlement expenses for the merchants from those APPs.
I think one of the major purpose of this eCNY is domestic - to dilute the financial clout of Alipay and Wechat pay. The longterm vision for this should be to eliminate all those APPs based payments. These app based payments are ones responsible collecting massive amounts of data and making a unimaginable sums of settlement money. They rival state power.