Well, this is a very interesting question. So, you need to understand that the color of our eyes between difference races might be different due to the difference of the gene type. However, the function of the eyes are totally identical to each other, green eyed and blue eyed people have the same function, despite their appearance. But maybe their sensitivity to lights could be slightly different.
There is no big difference between blue eyes and green eyes except the color. The color of eyes is fixed according to the genetic endowment which is determined by your father and mother. Usually many people will think the blue eyes are more attractive than the green eyes. However, you could wear the contact lenses to change the color of eyes.