Aurifil, Connecting Threads, and Craftsy all make 50 wt thread.
Big difference. Aurifil is 50 wt 2 ply Egyptian long staple. Connecting threads is 50 wt 3 ply extra long staple cotton Craftsy is Pima cotton. Masterpiece use to be 2 ply 50 wt but is now 3 ply 50 wt. extra long staple cotton. The manufacturing process and the length of the cotton fibers determines the quality of thread.