Difference is Koreans actually build high quality cars and Chinese build quality is debatable.
If the Kias I've driven are any indication... No they don't.
You also do realize that the Chinese make good stuff too right? It's not just the random brands you see on Temu and Amazon. It's the same brands you recognize already. Every Apple device for the past 25+ years is Chinese. Every component, every step of manufacturing, every human touch along the way. They're only designed in California.
China just has an excess of manufacturing capability, because they make everything for everyone. Hell, a lot of "counterfeit" and "knock-off" merchandise rolled off the same exact factory line as the name brand. The factories continue running manufacturing lines after hours to produce excess that gets sold on the grey market, and they also send the stuff that fails quality testing to the grey market.