Difference? Sure, but not great enough to consider them two different group of people, right? Even you pointed out there are so-called facial differences among Koreans (3 different types as I recall), are you saying they should not be mixed either? What, buknyonamnam is the way to go?
No, there are big difference.
This is why we often see DNA profiling of Beijing Han to Gaungdong Han.
Look at Koreans in China and Koreans in South Korea at above chart.
Comparing with Koreans is bad example because there aren't many Koreans compared to Chinese, totaling about 73 millions plus 6 million overseas Koreans. And Koreans today are basically product of Korean unity between Silla to Koryo. But I pointed out there are roughly three types of early settlers.
You still can't write in Korean don't you?
buknyonamnam? LoL, never heard this from someone called themselves as Korean.
You mean this? 남남북여?
'nam nam buk nyo,' and means 'South for men, North for women.'
It simply means South Korea have handsome men, North Korea have beautiful women.
Nothing do with describing ethnicity of Korea.