Do humans see colour as the same thing? Sure, we can look at something and say "green", but does everyone see the same thing?
It is my opinion that people generally see the same colors the same. I know it's fun and clever to think that maybe everyone sees colors differently and just calls them by the same name because of the way we learn language, but that doesn't mean it's true.
I think people see colors the same because people are largely the same physiologically and psychologically.
I also think so because people tend to associate the same colors with the same emotions - for example, blue is perceived as calming. I can already see someone objecting that perhaps blue is perceived as calming because of the places it's found in, such as the water and the sky, while still appearing differently to different people, but I think the experience of color itself is very emotional. It's vivid, strong, and unlike anything else. So I think the experience itself will cause certain feelings, not the associations provided by where colors are normally found. (Perhaps where colors are found played a part in their emotional meaning on a species level per evolution and maybe even morphic resonance.) Here is a list of color associations which also speaks on discrepencies in color associations across different cultures: Color symbolism - Wikipedia, the free encyclopedia
I think some people might see some colors differently, within bounds. Some people classify the same shade of bluegreen as blue while others classify it as green, for example. In the same way that language could account for everyone naming colors the same, language could account for people naming the same colors differently in this case, but it could also be due to the actual experience of the color.
Tests have revealed that the language used to classify color in a given culture correlates with how they group colors that are on a continuum as being most similar. This seems to indicate that perception of color, to some degree, depends on culture, and possibly on language. (I say possibly because correlation is not causation.) This effect is interesting but does not prove that people see color -completely- differently, and if it does suggest that, then it suggests that people of the same culture or language do see colors the same. I don't have a link to that study, but here is an interesting link I found just now by accident: Colour Words
Obviously color-blind persons and tetrachromats don't perceive colors in the same way. I am personally fascinated with tetrachromacy, which only happens in females and in a ratio of about one in 17 million.