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.
These are three new small stations. These stations have multiple turbolaser turrers, they can spawn fighters and they can rotate at the enemy direction.
Nice. :)
Are these buildable from the construction ships?
No, they are special defense stations from the new Super Shipyard station. This station does not build the SSD, it reduces the building times from all space units but it increase the price from all them.