Distance between Blue and Green

As for the traffic light, color of "To Go" is called "Green" in many countries, while people in some countries call that "Blue".
That is not only for the traffic light. Sometimes people call immature person as "green" in English, but in other language, they are called "blue".

What is the distance of blue and green?
Superficially just a distance in frequency spectrum?

Ancient people needed to symbolize all the facts in front of us to communicate in certain rule, I guess.
That's why they invented the word 'Green" or "Blue", area by area.
And that is linguistic system.

How could this symbolized linguistic system cover the area which occupy between "Green" and "Blue"?

Huge unknown crevice exists in our daily lives.
Still so many things we can find as an adventurous explorer!