It's probably the quality of the thread. I don't think C&C is extra long staple Egyptian cotton. The long staple is the key. Long staple means that the individual fibers are longer. Egyptian cotton is a type of cotton, not where it's grown.
If you do the math you'll find Aurifil is as cheap to use as C&C and it's finer, has less lint and doesn't have the slubs like C&C does.