Differential reinforcement in general is a scheduled procedure where the target behavior is being put on extinction by reinforcing something else than the original target behavior. It is not a punishment of the target procedure but does act to reduce that target behavior. The important thing is that the target behavior that is being reduced should not be reinforced during this procedure.
DRO (Differential Reinforcement of Other behaviors) is a time-based procedure in which reinforcement is delivered at the end of an interval if the target behavior is not occurring. Any other behavior, as long as it is not the target behavior for reduction, is rewarded.
DRL (Differential Reinforcement of Lower rates of behavior) Reinforcing a lower rate of the target behavior to decrease.
DRD (Differential Reinforcement of Diminishing Rates) Lowering rates of behavior using a progressively decreasing criteria
DRI (Differential Reinforcement of Incompatible Behavior) Reinforcing any behavior that would preclude the ability to engage in the targeted behavior.