Why can you recycle a telephone directory but not the yellow pages?

something to do with the yellow dyeWhy can you recycle a telephone directory but not the yellow pages?
We can recycle our yellow pages, here in Edinburgh. Our local Council takes them.
Am not sure, but aren't yellow pages printed on recycled paper? I do have the idea that you can not recycle paper an infinite number of times...Why can you recycle a telephone directory but not the yellow pages?
Our re-cycling collectors are bone idleWhy can you recycle a telephone directory but not the yellow pages?
yellow pages need sum
It has something to do with the colored pages I think.

estee lauder