The main difference is that laws in China generally prohibit the buying of foreign currency (except for importers) -- causing a situation where Chinese companie

The main difference is that laws in China generally prohibit the buying of foreign currency (except for importers) -- causing a situation where Chinese companies within China have to exchange the USD/Euro/Whatever currencies they receive for exports in to yuan. In Europe/the US, companies and citizens can hold on to that foreign reserve, which means that strong-handed efforts to peg a currency can rapidly tank the value of the local currency as confidence wanes. In China, there's no escape from the Yuan, so citizens just have to take the devaluation and loss of purchasing power.