My guess:
No.
Sorry…
When I was in High school a businessman from Japan visited the factory where my father worked. after their afternoon meeting/golf game, my father brought him home for dinner.
The area where I lived at the time has a large Native American population (Lumbee and Tuscarora), and the businessman was asking when he was going to see some Indians. We explained to him that they were all around him all day at the factory. He said, ‘No REAL Indians’. So we brought out an old American Hertiage book on the American Idians, and he was satisfied (Yeah… THOSE Indians!). ANYWAY, to the point of this post… he said that he could tell where in ASIA the tribes were from based on their facial characteristics… this one was Chinese, this one Korean, etc. etc. Always wondered if he was telling the truth, or pulling our legs.
This thread reminds me of a story Richard Pryor used to tell about when he visited Africa. In an effort to trace his heritage, he was asking an African to try to guess what tribe his ancestors had belonged to based on his appearance. The African looked at him and said “Italian.”
No, there is no difference. Bad news for people who sow ethnic discord: Pakistanis and Indians are the same damn people! Not that your intended to do so, Jargent. 
Pakistanis, no matter what they or others might like to think, are not different ethnically from North Indians. They are just Muslims (primarily) who moved to Pakistan 50 years ago at its creation.
There are fair-skinned Hindus from South India, and dark-skinned Muslims from Pakistan. Short of hearing a person speak or seeing their name, there’s no easy way to tell just on appearances alone. There are still multiple-ethnic groups on the sub-continent, but with the geographic mobility of today, you can’t tell where someone’s from just based on their ethnic/language group.
Oops, that’s “multiple ethnic groups”. No hyphen intended. Must preview.
Oh, I don’t know. I’m sure I’d be able to discern the respective ethnicities of quiet, naked, Asian girls. So…any volunteers? 
Irish-German-Russian mongrel reporting.
I have a Chinese acquaintance who swears he can tell by looking at you not only whether you are Chinese, but what part of China you come from, and that he can similarly distinguish Koreans, Japanese, Vietnamese, etcetera. I have never seen him actually do it, though.
I personally have met Uigurs from far western China and can vouch that those I have met look very different from most Chinese; in fact they looked more like Colombians than like Han Chinese. I also have fair success distinguishing Thais and Singaporeans from the inhabitants of the further northern areas, and of course most Indians can be easily distinguished from these groups.
But as far as distinguishing Chinese from Koreans from Japanese (or even, God help me, from Vietnamese) by physical appearance, I’m clueless. I can’t even tell the accents apart, though of course the names are usually a dead give-away.
Recently while we lived in Bangkok, Mrs. ShibbOleth, who is originally from Thailand, took a trip down to her mother’s hometown, Surat Thani, a smallish city in the south. She was walking down the street when, from nowhere, a stranger approached her and asked her, “Is your mother named Vanida?”
More than a bit surprised, she replied, “Yes, but do I know you?”
“No”, the woman replied, “but I know your mother. You look exactly like she did 30 years ago.”
Her family is of Chinese ethnicity on her Father’s side, which most Thai people are surprised to learn because they think her eyes are too large and round.
But when we visit southern California, many Mexican-Americans will try to speak Spanish to her. Which is ironic since my family background is Hispanic, so theoretically they should try and speak Spanish to me, but I don’t even look close. Yet when we lived in Germany most strangers immediately mistook me for German, which I am not one iota.
I would agree that your friend can SOMETIMES identify different Chinese who have a stereotypical look from one region. For example, the Cantonese have a stereotypical “moon” face. Sammo Hung might be an example of someone who “looks Cantonese.” My wife is Shanghaiese and has a typical Shanghaiese look. Actress Joan Chen has such a Shanghaiese face.
But, I would point out, that at most say 10% of the people of a region have that “look.”
Minority groups like the Uighers, Tibetans, Mongolians, etc generally have a very distinct look. They should as they have different ethnic backgrounds.
I’ve tried in vain to find a cite on google.com about a situation where the emperor of Japan mistook a Japanese citizen for a visiting Chinese. This did indeed happen and I did see a video of the meeting. If the emperor of Japan can make that mistake I suppose the rest of us can too.
Now that you mention it, when my Korean wife and I were in Mexico, she was often mistaken for Mexican (and told that she couldn’t go to my hotel room with me). When we’ve been in Thailand, she was constantly mistaken for Thai. To me she looks more northern Chinese than anything else, but she’s mistaken for a native practically everywhere we go.
Well, Thais tend to make the “Are you Thai?” mistake more than, say, Japanese, because unlike in Japan the Thais are not phenotypically homogenous. Thais are a melting pot of many ethnicities, including Chinese, Indo, Malay, Cambodian, Burmese, etc. The Thais you see driving taxis and the Thais you see on TV soap operas look nothing alike–much of it due to generations of intra-race class segregation.
My parents are both Chinese, but I get mistaken for Thai daily (I live in Bangkok.) Of course, when I start speaking English, they assume I must be a foreign-educated Japanese or HK citizen. You’d think a heterogenous culture would be more open to the idea of an Asian-American, but sadly the struggle continues.
The Thais who drive taxis are typically from Isaarn, and often either speak Laos or a dialect thereof. I have been told that most of the Thais in soap operas and modelling, e.g., the beautiful ones, are luk khrung, which translates literally to half children, but means Amerasian or Euroasian.