Rotors are sprinkler heads that rotate from side to side as they operate and are generally used for large turf areas. Sprays are smaller sprinkler heads that are stationary when active and are generally used for flower beds and small turf areas. Rotors need to be adjusted using a special plastic key (Hunter brand) or a small slotted screwdriver (RainBird brand).
Instructions for RainBird rotary heads can be found at: http://www.rainbird.com/landscape/products/rotors/3500.htm
Other helpful hints can be found at RainBird: http://www.rainbird.com/landscape/index.htm