I thought I can at least tell some difference in the appearances between Chinese. Japap. and Korean. But I thought wrong....its imposiable can any of u tell them apart ?

not really...I'm a total moron when it comes to guessing!

I can tell easily very easily! Koreans have light skin and their eyes are very sleeted with a bulge eye bag underneath.
Vietnamese have the westernised looks (maybe due to colonial-era french) so we usually have the western features, double eyelid (i dont know not one viet who does'nt have one)
Chinese, well its the way the person is dressed as well, follow the crowd of fashion i say.