Difference between 青い and 蒼い

This is a very small thing that I guess doesn’t matter too much. I’m at N4 and know blue only as 青い but I just discovered there’s also 蒼い. I looked up the difference and the first one says (blue, green) the second one (blue, pale) … so when should I use on or the other. Or is it like blue and light blue?

Thanks!