From what I understand from some quick googling, a non RAM needs 2 pairs of control surfaces to maneuver the missile, look at a Sidewinder, Sparrow, etc. A RAM is a simpler concept which loses some maneuvering ability in return for a cheaper simpler missile. The first RAM I believe was the Redeye SAM, followed by the Stinger, and the naval RAM. A normal missile has 2 pairs of control surfaces with attendant electrics, hydrolics etc and/or a vectoring nozzle. A RAM has 2 pairs of pop out control surfaces, 1 pair is fixed and canted to keep the missile rolling in flight, the other pair maneuvre the missile based on where they are in relationship to the rolling airframe, put simply, when they are in a vertical inclination they affect lateral missile movement, when in a horizontal inclination they affect vertical missile movement. Not bad considring I didn't know this 10 minutes ago lol. I have wondered myself, but never got around to finding out.
