From Conflict of Nations Wiki
Traditional towed howitzer artillery, mainly specialized in dealing anti-infantry damage. Can be moved by helicopter from mid-game onward.
Heavily armored front-line artillery. Especially effective at dealing anti-vehicle damage.
Multiple Rocket Launcher
Lightly armored, long-range rocket artillery, laying down an all-purpose artillery barrage.
Mobile Anti-Air Vehicle
Mobile, close-range anti-air support, specialized in anti-helicopter warfare. Can be secondarily used against infantry.
Mobile SAM Launcher
Mid-range, anti-air support unit specialized in anti-airplane warfare.
Theater Defense System
Long-range, anti-air support unit, focusing on anti-missile warfare.
Ground-based medium range radar unit, able to detect most air, land and sea units. Can gain stealth-detection later in the game.