I think that from quality, cost, and feature senses, there's lots of differences.

Quality - industrial diamonds won't have the flaws that natural diamonds do. In some cases natural flaws add value, but that's a rare exception.

Cost - the cartel keeps natural diamonds' prices inflated - so industrial diamonds win out again.

Features - read the HN comments I quoted from 2013 in a sibling comment - evidently the industrial process allows for some creative colouring via the use of various gases. It means that matching the common 'rare' colours of natural diamonds is quite easy, but also means there's a bunch of new colours and effects that you just won't find naturally.