Completely different circumstances. It's been explained ad nauseum that, at this point, if you still don't get the difference then i'm not sure what to say.
I'll try to summarize for you:
Previously:
Arena was downtown, similar to the braves. The braves realized the vassssst majority of families coming to games were in metro atlanta, anywhere from 30-90min driver to the atlanta suburbs where TONS of money (and population) presides. Braves moved and hardly ever have an empty seat now thanks to the move.
This new Atlanta hockey team is even MORE accessible to Metro Atlanta. Not only that, but all of the youth hockey teams
(sidebar: the city actually has a very active hockey community, including mens leagues and youth leagues; the state university UGA has a club ice hockey team that has become so popular that they are even building an arena for a club team; the state supports (easily) two ECHL teams who both thrive in attendance)
are all within maybe 30 minutes in every direction of the new NHL arena location as well. When studies were done to see what made NHL teams popular there was a strong positive correlation with number of youth teams in the area.
Put plainly, there is no way with the population and money that will surround the new team - not to mention tickets that will be nabbed by an array of corporate business - for the team to fail unless they have an uninterested ownership group not looking to invest a dime and sell the team as soon as they're able, like last time. If the ownership group includes some of the folks I've been told personally, like Anson Carter, then I highly doubt that will be the case again.