Could you post links to the two threads on Amazon?
I believe all the 50wt cotton thread that Aurifil makes is 2-ply mako. Also, look at the photos. The 50wt 2-ply Aurifil I buy and love for both piecing and quilting on my domestic machine comes on the orange spool. I just checked the different spools of Aurifil I have and they all say on the bottom "Mako ne 50/2" meaning 50wt 2-ply.