Core mechanics are probably going to be identical to what we see in EotE.
Obligation will probably be replaced with something that has more of a military theme. Possibly same too with the Careers, though many of EotE's careers and specializations can already easily be reskinned to work in an AoE campaign without needing to completely redesign. It's a very short leap from a Hired Gun to a Soldier or from Colonist to Diplomat. Explorer and Mechanic could probably be left as is, with only Bounty Hunter and Smuggler really needing a revamp to be less Fringe-based and more military-based. A lot of the talents also work just fine regardless of campaign focus, so expect to see a lot of those cropping up in both AoR and Force & Destiny; again why reinvent the wheel?
I don't necessarily think that AoR PCs are going to be inherently more powerful than EotE PCs, but they might be qutie as strapped for credits during character creation.
I'm kinda hesitant to speculate on species, as we don't know what EotE is going to have when that comes out, but if Mon Cal aren't in the EotE core, then it's a safe bet they'll be in the AoR core.
Minions will probably be expanded to allow for large-scale combats. Maybe not full-blown Battle of Hoth (except on a very high-level view), but things like the Battle of Endor would be a safe bet.
If the theory that each core book reflects one of the Original Trilogy movies holds, then we might see a broadening of Force material, as ESB was when Luke really started to grow as a Jedi. Not full-blown Jedi Knights mind you, but some expanded options, maybe even a new Force Power or two.
The one thing we'll definitely see that's different is a lot more combat-focused vehicles, such as Rebel snowspeeders, X-Wings, B-Wings, Star Destroyers, Mon Cal crusiers, and the like. Going with the large-scale combat expansion, we'll probably see rules focusing more on multiple ship combat as opposed to EotE which seems a bit more focused on one or two PC ships (presumably based on the intention that the PCs in EotE start out with a light frieghter).
I'm also not convinced that we're going to see a Beta for AoR. I admit it'd be pretty sweet, but it feels like a large part of the rationale for having an EotE Beta was to put FFG's rather novel new dice system into the hands of players and derail a lot of the potential negative press that would have been generated in the months prior to EotE's actual release. Now that FFG has their validation that the dice pool works according to how they designed it, there's really not as much of reason to do Betas for the other two books.