Blue and purple are very different from differentiating between red and green. Red and green are opposites - blue and purple are next to each other on the color wheel. A lot of people have trouble telling the difference between blue and purple.
I've had ON two times in my left eye and some of my color vision came back. HOwever, things still are a wee bit different colors when I shut one eye versus the other. But, it is not a drastic change at all!