Kirk D. answered 07/02/19
15 year High school Film as Lit teacher and life-long film aficionado
Since the director and the editor have two different jobs that happen to depend upon each other for the end result of the film, there are occasional discrepancies between what the director's vision of the film was versus the editor's vision. The average movie watcher may hardly notice a difference, but it was important enough to the fans and/or critics that the other "Cuts" be released.
Theatrical cut usually has to do more with running time or inappropriate content. If a film surpasses the 3 hour mark, it is harder for theaters to capitalize on multiple showings in a day. Longer films are also harder sells to the general movie watcher. When the film is eventually released on digital (or whatever format), after its theatrical release, there may be a "theatrical cut," which is what most people saw in the theater, and the "director"/"editor" cut (see notes above).
I hope this helps.