While both are centered primarily on the use of troopers and mechs, there's more than enough variety between the two sides, both of a practical and philosophical nature. Like the new film, the game adds two new political factions to the Star Wars universe: the Confederacy of Independent Planets and the Galactic Republic. But now, concurrent with the release of the film, LucasArts has released the first expansion to Galactic Battlegrounds, The Clone Campaigns.
Not that that's a bad thing I loved Age of Kings and I loved Star Wars. I remarked at one point that Galactic Battlegrounds, based off of Age of Kings, seemed like little more than a Star Wars themed expansion pack. Released as an add-on for The Age of Kings, it added tons of new units, loads of new campaigns and some thoughtful rebalancing to the existing game.
It's probably still safe to say the The Conquerors was my favorite expansion of all time.