I've used both CT 50wt and Aurifil 50wt. Aurifil is a much thinner, finer 50wt - quite noticeable when you finger it. Part of the reason is that Aurifil is 2 ply and CT is 3 ply, but I think overall Aurifil is a better quality long staple than CT. I found CT to be so linty after just a few yards that I couldn't see what I was doing (and I was using a larger needle). I traded it all away and have converted to Aurifil.
When I look at a spool of CT I can see the little fuzzy hairs on the thread - still on the spool. It also has a dull finish. These reasons combined with the results of using the thread lead me to believe that it is not a quality long staple thread. Look at a spool of Aurifil - smooth, bright and lots of sheen to it. Beautiful stuff.