There are six facilities built on Earth rather than one.
The facilities and the cannons themselves are notably larger, at least double the size of the original Stonehenge.
There are three jammer towers in the center of each facility, rather than one small jamming facility.
The explosion effects are visually upgraded, and look similar to the explosions of burst missiles.
Stonehenge's attacks no longer "blanket" the sky above 2,000 feet. It seems to be safe to fly above 2,000 feet, but the unpredictability of where the shots will strike is still a problem at long range.