Modify

On a second thought, chopstick is a lingua franca of the Chinese culture.

Like everything else in life, it got modified slightly wherever it goes:

In Korea, chopsticks are generally made of metal (iron or silver); using wood or bamboo ones are considered as a sign of poverty.

In Japan, chopsticks have pointed tips (as compared to the blunted end of traditional Chinese chopsticks, which remains the standard design of disposable ones in Japan). For that seemingly trivial modification, there is, in fact, a substantial difference in the proper way of holding them.

On that last point, I shall not elaborate on the actual techniques. Suffice to say, a skilled user of the Chinese chopsticks could easily use his instrument to cut out a piece of flesh from, say, a whole fish – a task that is not meant to be done by the Japanese equivalent, however dexterous the user is. Of course, the explanation is obvious: We serve whole fish or other cuisine in big dishes, and there is often a need to dissect the object for sharing; in Japan, meals are generally served individually.

(Another contributing cause is that Japanese rice is slightly more sticky – or, in scientific terms, has a higher content of gelatin – for which it is less messy to use chopsticks with small pointed ends. Just try it yourself.)

PS. It is a common belief (and in fact quite scientifically proved) that chopsticks take part in the spreading of infections that could be transmitted via salive (notably Helicobacter, the cause of peptic ulcer). However, the blame is not entirely legitimate. A noble Chinese with an appropriate upbringing should finish with his dinner without soiling his chopsticks – each piece of food is diligently put into the mouth by a non-touch technique.