It's just a marketing thing. Dragon has used various "lines" to showcase or highlight similar qualities. Throughout their history they've used titles such as "Shanghai-Dragon", "Cyber-Hobby", "Smart Kits", "Generation2", "2-in-1", "3-in-1" labels. Now "Black Label".
What was the difference between a "Mercury" car versus a plain "Ford"? A thousand bucks.
The kits released under the Black Label series are:
1/35
M103A1 US Heavy Tank
MBT-70 (KPz 70) US/German tank
M6A1 Heavy Tank
1/700
USS Zumwalt destroyer
Annoucneced are
1/35
British Conqueror MBT
British Saladin A/C
M103A2 US Heavy tank
1/72 M65 Atomic Annie cannon
The issue with the "Black Label" series is that it seems to have started off on the wrong foot. The M103A1 and M6A1 were panned for inaccuracy -- especially the M103A1. The MBT70 had bigger issues -- no one seems to have finished the M6A1 yet. These follow the T28 Assualt tank (not under the Black Label series) that had some big inaccuracies too. These all combined to cast some the recent releases in a very negative light. One builder on Armorama re-worked the M103A1 to accurate standards -- it was something akin to building one of the pyramids, it seems!
Because the subjects gained lots of excitement, the subsequent disappointment was very loud too. I certainly don't think the DML execs thought these would be considered "last on the list" -- as they clearly should have anticipated the excitement given the subject matter. Remember, every kit is a HUGE investment in development, design, manufacturing, marketing and distribution.
This doesn't take away from some extremely nice work that DML is issuing month to month. I have no reason to jump on the bash-DML bandwagon -- I'm still building kits they issued ten years ago that have been in my stash! Some US Halftracks and the M7 Priest. I'm loving those -- fantastic kits.