In LDOCE, 'light' is considered a synonym of 'pale' which means having more white in it than usual, and I also thought pale and light are interchangeable when it came to colors.
I'm reading 'English Vocabulary in Use', intermediate level by Cambridge University Press which is based on British English, in which there is a note that says,
Note: With some colours, we use pale, not light, e.g. pale yellow.
Firstly, Is it something exclusive to British English?
And secondly, what are the other colours that you refer to as 'pale' and not 'light'.
I took a picture of the page in the book. Just click on the picture. You can find the Note on the left.
Best Answer
Technically "pale" refers to the saturation of the color, and "light/dark" refers to luminance, or the perceived brightness.
In AmE usage however, light can also mean a color that is not intense. I can't think of an instance where pale could be used for a color that is intense but light (or bright).
As I mentioned in my comment, in general conversation, you can use pale or light interchangeably when referring to a color and be understood. If the register is more formal and you're writing for a UK English audience, you should follow the advice in your book just to be certain your phrasing won't seem odd.
For each of the examples below, I went to DuckDuckGo.com and searched for images that matched the term. I had success with each color except for pale dark green - I ended up searching for "pale dark green" fabric to find an image where the color filled the frame. I picked from the first few results the ones I felt were distinct enough to show the difference. There is not a definite line where we can say "this green is pale to everyone who looks at it". Click on the image to see the original sized image.
This is both a light green and a pale green:
This is a light green but not a pale green:
This is bright green (both light in luminance and intense in color):
This is a pale dark green (might also be called gray-green):
This is a dark green (not pale This color is often called emerald or emerald green):
