I can be too observant for my own good but I don't think this is one such instance. And oh no, nothing like that. Basically part of what makes Six unique is the ability to film the MegaSix at the end, the alternates having their own costumes and then having set dates for the alternates to go on in the different roles to also allow the principle cast to rest because it's 9 shows a week instead of the typical 8 shows a week. But because of Broadway rules, no filming of the MegaSix, the alternates will have their own version of the principle costume and it seems no set dates for the alternates for when they perform.
There are other difference - the lighting which just based off someone filming the first MegaSix are amazing and dialogue to reference it and tweaks to the costumes - but those aren't the same as changes to some of the more unique aspects of the show.