I myself am Chinese and I have found that people often confuse between people of these countries so I will try my best to explain the difference.
Before I start, I would like to say that none of the things I am saying is meant to be offensive in any way. Also, the information may not be 100% accurate; it is just the way I tell the difference. Also, please comment and let me know of ways which you use to tell the difference because I’m interested to know.
I am Chinese so I grew up around Chinese people which makes it easier for me to tell the difference in the same way someone English would probably be able to tell the difference between England and German people. I admit that it is quite hard to tell the difference without hearing them speak and you can’t be right all the time but it is possible to guess correctly which nationality they are.
Here are some of the ways I use to tell the difference:
1. Skin Tone
As I said this is not always true but in general it is. Japanese people tend to have a lighter skin colour than Chinese people. The difference is subtle but I would estimate that it is true for every 5 in 4 people.
2. Eye Shape
Personally, I never really liked it when someone commented about the size and shape of eyes. However eye shapes are an important part in identifying between the two nationalities. I find that Japanese people’s eyes sometimes – but not always – angle slightly more upwards than Chinese. Likewise, some Chinese people’s eyes angle slightly downwards. This is not always the case as many have eyes which do not angle upwards or downwards but it is more likely for someone Japanese for their eyes to angle upwards and vice versa for Chinese.
I would also like to state that Chinese/ Japanese/ etc people do not always have smaller eyes but they may seem smaller because of the way their eyelids are and also the way Europeans’ eyes tend to be more deep set.
3. Hair Colour
Although most Asian people have black (very dark brown) hair, their is a difference between how dark it is. I find that in general someone who is Chinese has darker hair than someone Japanese. Though this can be unreliable as a lot of people dye their hair and it is fashionable in China to have brown highlights.
I’m not going to talk about their personalities because I believe there is no ‘typical’ Japanese or Chinese. Everyone’s personality and the way they act are different so if I tried to sum it up I would just be stereotyping. Judging whether someone is Chinese or Japanese can be hard and there’s no harm just asking the person whether they are Chinese or Japanese. It can be a lot better than just staring at the person trying to work out which race they are from!