It focuses on the Mingus-led sessions, excluding his sideman work, and adds in the essential 1966 "Right Now - At The Jazz Workshop" album with Jordan, Handy, and Jane Getz. It is a much more solid set - there was a LOT of dross on the Complete box (IMO, YMMV, etc.). I sold the Complete box, bought this Leader box and the most important (to me) of his sideman Debut sessions - Paul Bley, Hazel Scott, the Trombone thing with JJ etc. I got the John Dennis CD as a cutout. I already had standalone Quintet and Powell Massey Hall CD's. I have not regretted my decisions.