Alliance are a serie of different mods. On the Star Wars GC, you can play the civil war Empire vs Rebel era + Black Sun and soon the Republic and CIS.
There are many new improves on galactic conflicts tactical events, I have edited all the triggers starting them many time before previous versions and I have added some small new things as you can see on screenshots.
Other new things are a Empire at War GC with only 28 planets and the Trilogy of Jedi Academy + Dark Saber joined on only one GC.
The biggest news is a new GC with all the tactical events from all the GC, from Episode IV to the future. Have fun.
It like empire at war.
It is. It's the Alliance Mod for EaW.