Sheesh, I can recognize the difference between a “significant” percentage of Han Chinese, non- Han Chinese, Koreans and Japanese. Now to qualify that, I don’t know if it’s 20% or 50% or how much it’s based on non-facial markers like dress, posture, etc. I’ve lived 20+ years in Greater China and 2.5 years in Japan. And I will admit it’s a lot tougher to do this with 3rd generation American East Asians dressed up like trendy gangsta wannabes.
Just a guesstimate, but probably 20% (or 40%???) of Korean, Japanese and Chinese have an obviously racially identifiable look. And there’s probably chunk that just look East Asian of some sort. After all, 8% of Asian men are descended from Genghis Khan in the strictly male line. (Thanks Chronos): Family and descendants of Genghis Khan - Wikipedia
Even among the Han Chinese, there are ethnic looks. It’s definately a lot tougher to distinguish than say between Han and Korean. However, there’s a group of Shanghaiese that look, well, Shanghaiese. Actress Joan Chen has a very stereotypical Shanghaiese face as does my wife. There’s a very stereotypical Taiwanese and/or Fukjian “look” that dunno maybe 10% have. Shandong Provice people tend to be really big and broad. Northerners are tall. Cantonese tend to have a typical non Mongol short and squat look. This is all without looking at how they dress, move, act or speak.
Non ethnic Han like the Tibetans, Mongolians or Manchurians really stand out. Of course the Uighur’s or Kazak’s have a cacausian look.
Now, clean 'em all up, put them in a school uniform, glasses and a standard school haircut, and it gets tougher. 
Just this morning, while waiting for my kids school bus, a woman riding her bicycle stood out as most likely Philippino but definately some sort of SE Asian non-Han. She stood out like a sore thumb.
Even Sven, you have ***one ***valid view of China, but dang those Sichuanese can be ignorant (in an unexposed, unexperienced and unquestioning way). Your Philippino friend wouldn’t get that treatment in Shanghai at least. And a Shanghaiese wouldn’t get faked by a casual Westerner claiming to be Uighur. China’s a big country and there are a lot of valid and contradictory experiences here.
I’m with **Septimus **in that I could get a better than random score distinguishing between Chinese, Korean and Japanese.