The games are similar but much different in terms of complexity. SL got bogged down by its rules but ASL is hands-down the best wargame I've ever played.
Propaganda makes your opponents' population defect to your country. There are a myriad of delivery systems and warheads that must be matched together to be played, including Killer Satellites, Space Platforms, Cruise Missiles, MIRVs and the "SuperVirus", which roams around the table randomly wiping out population due to plague.