Can see only grey?
Mixes up colours?
Some colours look the same?
I worked with a guy once who was trying to convince me that he was colourblind. He said that for him, a traficlight's lights was changed around.
He said that the green looked like red and the other way round. (BTW he was a @sshole)
If I learned that green is green how would I ever know what green looks like to you. Maybe what I see as green, you see as brown but you learned that it was green.
Eish I hope you understand what I mean cos I'm not sure I do anymore

The way I see it is that some people has a hard time telling the difference between colours that are close to each other. Blue/green Red/brown etc...
Can someone please clear this up.