I have observed several people over the years refer to something that is orange in color as "yellow". Is that some linguistic difference or a difference in perception?
Orange is one of the newest colors, in that in most languages, it was still considered merely a shade of a different color (red or yellow) up until recently. My favorite example of this is the pigment red lead, which isn't red at all, but bright, almost-neon "construction orange". And of course the hair color of most redheads isn't red either.
I don't have any similar examples for orange=yellow, at least not in English, but I could totally conceive of someone describing, say, a leaf as yellow, even if technically its color fell closer to the orange spectrum than to strict yellow.
 In English, early 16th century. The color was named for the fruit.
 The Hungarian word for a carrot is "sárgarépa" = yellow beet.
It can certainly be a difference in perception. My wife is mildly color-blind, and we sometimes describe the same item with different color words because we perceive it differently.