Sounds like as of this week, the developer is giving up on Eternity, pushing a few more updates to the original game, and then leaving it in the hands of the players to work on. Seems the community moved back to the original anyway for the most part, as Eternity was just a pointless rebuild of a game that was fine to begin with. If you're going to play, I'd bet on the original game being the one with staying power. Don't invest in this one.
You can read this to understand the difference between the games, besides just the UI:http://steamcommunity.com/sharedfiles/filedetails/?id=290092757
Yes, it does seem like Eternity has more content overall. Maybe someday someone can port some of it down to the original. Until then, it seems like people are willing to live without it. I just checked the player counts right now. The original has 825 and Eternity has 53. It will only become more lopsided in the future.